Related Local Links:
Lens and Camera Testing Pages
Lens Color (and Testing)
MTF charts
Blind Lens Testing
Related Links:
Leica vs. Zeiss Lenses (Mike Johnson)
Lens Distortion and Color Fringing Tutorial [5/2002]
Lens Testers Anonymous
Lens Testing in the Back Yard (by Jim Bullock) [8/2003]
Pentax Lens Test Pages
Vignetting Tests
Exercise the aperture stop-down ring by moving it from slowest to fastest
apertures and back. Is the action quick? Are the springs tight and strong?
Or does the lens stop down slooowly? Look at the aperture blades,
especially for oil or other signs of friction wear or damage. Now exercise
the zoom function (is there is one) and focus the lens slowly twisting the
barrel from side to side at each setting. You are looking for jumps or
binding in the focusing mechanics which could indicate internal damage,
wear, or poor repairs.
Another easy tell-tale is the front of the lens. Is the filter ring
dinged? If so, the lens probably has a history of hard impacts, which
could easily dislodge and decenter lens elements, reducing lens
performance. Scratches on the lens tell a similar tale. Look at the rear
lens element in particular. Our lens
faults pages give you a hierarchy of lens problems.
Probably 90% of the lenses out there are okay (maybe 70% on EBAY, versus
say 30% of the bodies!). Without using film for a test, you can't be
really sure how well it will perform, or if there is not some subtle
problem with it. But the above tests will identify most of the bad and
abused lenses out there, and greatly improve your odds of getting a good
one!
You can learn a lot about how well a lens performs with just one roll of
slide (or print) film. You will need a steady support, preferably a
tripod. To prevent camera shake, you can use a cable release or the
self-timer in many cameras today. I prefer to test lenses on overcast
days that would be cloudy bright.
Find a subject with known straight lines, preferably vertical or
horizontal or both. I usually pick houses with aluminum sidings that are
lighted so it is easy to see the lines. Other folks use venetian blinds in
windows. Another favorite source for testing distortion are those downtown
skyscrapers with lots of windows and lines in their facade. Be very
careful in leveling your tripod, using a bubble level if available
to keep it level.
Don't make the mistake of projecting your slides and trying to measure
distortion on the big screen with a ruler. Sorry, but the enlarger lens
and tilted projection setup will again be more distorted than the lens you
are trying to test.
Instead, look at the slide or negative under a high
powered loupe. You need a true, thin straight-edge to evaluate distortion.
The easiest one is a clean and unused safety razor blade or something
similar. Carefully line up the straight-edge with the lines in the slide.
Usually the worst distortion will be at the outermost lines. Now check and
see if you have either barrel (bulging out) or pincushion (bulging in)
distortion present. You can use this technique to compare two lenses for
distortion in a general way.
In theory, you can use a straight-edge metal ruler with tiny distance
markings on it to estimate how large the bulge is over a measured
distance. The ratio of the amount of distortion could be expressed as some
percentage. In practice, most fixed lenses have distortion below 1%, which
is hard to see even with a straight-edge, let alone measure accurately.
Even zoom lenses average around 1.5% or less distortion, but a few low
cost ones might be as high as 3% or so (readily visible even on
enlargements).
I should also add that for zoom lenses in particular, the amount of
distortion can vary a great deal depending on the focal length setting.
Some zooms even go from moderate pincushion distortion to modest barrel
distortion as you zoom the lens through its settings (i.e., a compromise).
Some lenses (e.g., wide angle zooms) may vignette if used wide open.
This problem will show up best at the widest angle setting on the zoom
with the lens open to its maximum aperture. You will see some darkening or
light falloff in the corners. Stopping down will generally improve the
image until the vignetting is eliminated, usually one or two stops down.
Another common cause of vignetting is using a thick filter on an ultrawide
angle zoom. For example, I have a 17-28mm zoom which vignettes at the 17
to 18mm settings when I put on a 72mm red filter (for sunsets). The filter
is too thick, and cuts into the photo, producing curved edges on the film.
Special thinner filters are made to prevent such image vignetting with
wide angle lenses. This issue is yet another reason to test your lens
without a protective filter in place, and then again with the protective
filter (if you use one). You will know if the problems with vignetting are
in the lens, or the use of the too-thick filter.
To avoid these problems, you would have to test the lens at the widest
focal length settings. You might also run a series of tests at different
f/stops to pick the sharpest settings or "sweet spots" of your lens. These
"sweet spots" will be where the lens will work best in terms of resolution
and overall performance. A few pro lenses such as fast telephotos may be
optimized for wide open performance. Here again, you would want to know
this when using the lens!
Chromatic aberrations can most easily be detected by looking at color
slides under a high power loupe. Do you see any color fringing, especially
around white subject lines? If you see a bit of red or blue coloration rim
around subjects where there shouldn't be any, you may be seeing such color
aberrations (or coma - however, coma will improve with stopping down,
these color aberrations won't). Such problems are usually easier to see in
the extreme edges of the slides.
Curvature of field shows up when some areas of the image are in sharp
focus, while other areas are less sharp. To detect this reliably, you have
to use a really flat subject such as a page of newsprint. You also need to
be sure the camera is level (using a bubble level and tripod). If you see
one area is soft or less sharp, or the center is sharp but the rest of the
image is less sharp, then you may be seeing field curvature
problems.
You can
test for spherical aberrations by carefully focusing the lens wide open on
a sharply defined nearby subject. Now stop down and check the focus. If
the focus has shifted, then you may have a degree of zonal spherical
aberration. Not everybody can do this test well, especially with a dark
screen image, but give your eyes time to adjust to the darker image and
check the focus for shifts.
Ansel Adams (in his Camera and Lens book) suggests a trick for evaluating
focus shifts. Pick a subject with a bright metal surface with a bright "specular"
highlight. The highlight should be small in area, so it can be sharply focused. As
you stop down, the rest of the scene will get darker (especially in a view camera at
smaller f/stops like f/45 or f/64!). But the specular highlight should still be readily
visible, and easy to use to focus sharply.
Adams also notes that many large format lenses can be unscrewed into sections, with each
section used separately. This trick provides several focal lengths from a single lens, one
for each section apart, and a shorter focal length for the combination. But in older
lenses, the overall corrections (e.g., for spherical aberration) are best only for the
assembled lens, with the individual cells having poorer correction. Adams cites an (unnamed)
famous photographer who failed to realize that serious focus shift would occur with only
one section of the lens in use, ruining many otherwise excellent images. Focus shifts are
also encountered in misaligned lenses, and in lenses in which an inept repairer has flipped
a lens element in replacing them in a repair job.
The lens coatings may be colored magenta or blue or other colors to the
eye, but they don't impact the lens color in the above test. We don't use
film for this test, as films have color prejudices of their own. Be sure
that the light source looks bright white, as from a daylight fluorescent
or white light bulb or mid-day sunlight source. The paper should appear
bright white for best results.
To evaluate visible flare, you can take a photo of a bright point light
source such as the sun. You may see a hexagonal or other pattern from
reflections off the surface of the lens diaphragm blades. You may also see
bright blobs or streaks of light reflected from lens elements. Try a shot
without your UV filter, if you use one, to see why some of us don't use UV
filters (they add to flare). Some lenses such as my 20mm f/3.5 AI nikkor
have surprisingly little flare, even in direct sun in the photos shots.
Zoom lenses tend to have much higher flare than other lenses due partly to
the larger number of elements having more reflective surfaces. Again, this
is one major reason many of us prefer fixed or non-zoom lenses.
| The question of subject distance when testing a lens is important. Photographic lenses are normally optimized for middle distances, say, six to ten metres, the range in which they may mostly be used. The wider the aperture, the narrower the optimal range, a factor important from f/1.4. Source: Lens Test Charts by Geoffrey Crawley in British Journal of Photography, January 31, 2001, p. 26. |
One of the flaws commonly cited for the PHOTODO lens test site is their use of infinity for all
lens test distances. This is a modest error for most lens designs, but a serious problem with
some 35mm macro lenses. These macro lenses should be tested at the distances they will likely be
used, which is presumably for closeup macro work. Tested at infinity on an Ealing MTF test machine,
and they provide disappointing MTF scores.
Many lens test charts are standardized to test at 25 times the focal length of the lens (cf.,
USAF 1951 charts). At these distances, the chart can be readout directly in lines per millimeter
resolutions. Unfortunately, a 50mm (2") lens, at 25 times the focal length, is only 50 inches
from the test chart. The same lens is probably optimized for 20 or 25 feet. In other words, we
rarely test the lens at its optimum focusing distance. There is some error here, and how much
depends on the lens and testing distances used.
Then I made the mistake of trying to show how my pricey Nikon kit was superior
to my cheapy Minolta SRT101 setup. Bad mistake. I shot each camera with the same
slide film, side by side on the same scene and identical lighting (one
shot and different cameras and lenses right after the other), on the same
tripod, with the same lab doing the processing. I could see some minor
differences, but that Minolta lens was surprisingly good. I picked up a
$17 used normal lens for my Spotmatic. Surely my Nikkor would blow it
away. Ooops! These normal lenses were all so good that you could hardly
tell the slides shot side by side apart. Maybe it was just me? So I asked
some friends and students to try and tell them apart. They were equally
surprised by how good the other lenses were.
Some years later, I found myself on a tight graduate student budget, and
unable to afford most of the exotic OEM (nikkor) lenses I wanted. So I
decided to settle for some third party lenses. I "knew" they'd be awful,
based on what everybody had told me. Unfortunately, I decided to see just
how terrible they really were. To my surprise, these lenses did pretty
well, often as well as my nikkors at mid-range (diffraction limited)
f/stops.
I reached the nadir of lens prejudice when I decided to find a "bad" lens
to destroy it in some tests to see how bad scratches and even cracked
glass would impair lens performance. But first I needed to test the lenses
to see how bad they were before I scratched and bashed them up,
right?
Yes, testing these $10 to $15 US lenses was another bad mistake. I bought
a 28mm f/2.8 AI lens made by Osawa. Surely this junker would be awful.
Well, it was - awful good that is. It turned out the dang lens was very
nearly as good as my much more costly Nikkor 28mm. Hmmm?
As an aside, slight underexposure (one stop) gave even more impressive figures at full
aperture (80/65) and slightly inferior results at f/11 (80/80) and below, while slight
overexposure (one stop again) was inferior across the board:
| Pan F plus with Color Skopar 21mm f/4 Lens | ||
|---|---|---|
| F/stop | Over-exposed (lpmm) | Properly exposed (lpmm) |
| f/4 | 65/50 | 80/50 |
| f/5.6 | 65/50 | 100/80 |
| f/8 | 80/65 | 100+/80+ |
| f/11 | 80/50 | 100+/80+ |
| f/16 | 65/50 | 80/65 |
| f/22 | 50/50 | 50/50 |
This shows the importance of not over exposing if you want optimum sharpness!
As you can see from the above table, over-exposure "cost" us about 20% on average, but
at f/5.6 we lost about a third of both center and edge resolution (100 lpmm to 65 lpmm
and 80 lpmm to 50 lpmm respectively).
I am adding this caution about exposure errors here because it highlights an issue that
isn't often discussed, but which has a big impact on your lens testing efforts. A 20%
difference between two lenses would generally reflect the difference between the very
best OEM lenses and the not so stellar third party offerings at far less cost. But here,
such a difference could be due simply to an over-exposure error (e.g., lens T-value or
transmission might differ).
Conversely, someone wanting to pump up the wide open performance values for this lens might
under-expose by a stop. The result would be even higher lpmm center and edge values wide
open. This observation is also interesting in that many fast lenses, used wide open in dim
available light yielding a modest under-exposure, may be performing better
than if they had been properly exposed.
From: [email protected]
Newsgroups: rec.photo.equipment.misc
Date: Mon, 05 Mar 2001
Subject: Lens Testing Kit
Please go to href="http://wdn.com/~johnchap/lenstest/testlens.htm" for
some description and links to the instructions which you can download
and print out. Also Included in the material are the resolution
charts which are needed.
The material will instruct you how to set up the charts, shoot the
tests, and interpret the results. I have always found it very
enlightening how certain lenses do. The results you will get may very
well surprise you. I have found several inexpensive lenses with
excellent optical quality. On the other hand, I have found some very
expensive lenses that are not nearly as good as their much less
expensive brothers.
If you encounter any problems, have any questions, or have any advice
how I can improve access and usability of the site, please email me.
[Ed.note: some counterpoints...]
From: Bob Salomon [email protected]
Newsgroups: rec.photo.equipment.misc
Date: Mon, 05 Mar 2001
Subject: Re: Lens Testing Kit
Bear in mind:
Most lenses were not designed to be used to photograph a flat piece of
paper at close range.
The results that you get are determined by:
a: film used b: exposure c: processing d; lighting e: contrast f: atmospheric contaminants g: loupe used h: how tired or rested your eye is
That means that these tests are at best non repeatable and at worse
worthless.
The proof of a lens's performance is not how it photographs a flat piece
of paper - unless it is a process lens- but how it handles everyday
photographic work.
That is why camera and lens manufacturers stopped photographing flat
pieces of paper decades ago and switched to a repeatable test - MTF
...
[Ed. note: and a reply...]
From: [email protected]
Newsgroups: rec.photo.equipment.misc
Date: Wed, 07 Mar 2001
Subject: Re: Lens Testing Kit
I am not sure what point you are trying to make. Nevertheless, while
I agree with some of your points I do not with others. My tests are
as standardized as I can make them, given that they must be conducted
outside due to the lens to target distances. They are always
conducted in direct sunlight using the same film and same developer.
A known standard lens is always included in every test episode. Using
electronic flash would be more consistent, but with the distances
involved that proved impractical. When possible, I conduct a lens
test using both MF (with focusing magnifier) and AF.
Lenses that do not focus on a plane are said to have excessive
curvature of field. That is, a good lens will be able to focus well
on a flat plane. Secondly, what do you mean by close range. Since my
target area is fixed in size, the image size is the same, regardless
of the focal length of the lens. This means that with long lenses I
am not close to the target. I have not actually paced of the
distances, but I suspect with long telephotos the lens to target
distance 100-200 feet.
High resolution is a necessary but not sufficient condition for high
lens quality. If the lens cannot resolve the lines, it is not a good
lens no matter how well it does in the other factors of lens quality.
Distortion, contrast, accurate color, etc. are other important
factors, but are much harder to quantify, especially without more
sophisticated equipment.
While I do accept that there are variations between testing episodes,
I try to minimize the impact by including in each episode one of my
standard lenses for comparison purposes. Then in each episode the
lens(es) being tested in compared to my known high quality standard on
a relative basis.
Also, it seems to me that when I am evaluating a lens, the lens could
be better than the results I am evaluating, but it can not be worse --
at least in terms of resolution. If I have results showing resolution
of 60 lpm, then the lens (at least the sample I have) can resolve at
least 60 lpm at the distances used in the test. I test lenses at
three different distances at the two widest apertures. With better
focusing, or less wind, or a higher resolving developer or better
loupe might result in better figures. But once I hit an acceptable
level (for me) of lens performance, I do not worry about maximum
performance, since it is seldom achieved in practical real life
picture taking.
If the results of a lens with a good reputation come out mediocre, I
retest the lens. More often than not, the original results are
duplicated. One example of this is the Tokina 20-35/2.8 . Over
several testing episodes my cheap Vivitar 19-35 produced better
resolution figures than the Tokina, particularly in the corners.
And, in practical picture taking, the Vivitar produced sharper photos,
particularly in the corners. I have yet to encounter a lens that did
not perform in the field consitant with my test results.
To again address your criticism about photographing a flat piece of
paper.... If the lens cannot photograph a flat piece of paper, then
the lens falls short of where it should be.
As to MTF, I have a loupe (several actually) some targets and a
standardized test procedure. I and most other photographers do not
have the time or equipment to deal with more precise, and perhaps more
sophisticated test procedures.
And if what you say is true that manufacturers no longer test their
lenses on two dimensional targets as one of their tests, then it could
be the reason there are so many mediocre lenses on the market; lenses
that would have difficulty producing even a sharp 8x10 let alone
something bigger.
....
From: [email protected] (Richard Knoppow)
Newsgroups: rec.photo.equipment.large-format
Date: Thu, 12 Apr 2001
Subject: Re: Me too, me too, I want to do a lens test.
"annqlee" [email protected] wrote:
>Hi All, > >I finally got my Air Force Resolution Chart for a photography project but >I can use it for its intended purpose also! But I don't know how far to take >it and how much of the chart vs frame to take? I don't even know if it would >be useful. >Just wondering if anyone care to see some results for > >1) 360 symmar/630 2) 150,300,210 geronar 3) 360 Caltar II-N (sironar) 4) 200 >Grandagon >5) 240 symmar/420 6) 90 Super Angulon 7) 90 Super Angulon MC 8) 210 APO >symmar >9) 210 Sinaron-S 10) 135 Nikkor W 11) 210 symmar/370 12) 165 Super Angulon >MC. >13) 150 Componon-S (as a taking lens) > >I can only do it on 4x5 Delta 100 (getting rid of it). Any suggestions? > >Thanks, > >Ann
Lens tests with a test chart can be revealing but need some
understanding of the limits of the method.
You can photograph the chart and measure the resulting resolution on
film. This is a test of the entire system. If the resolution of the
film and the lens are about the same the resulting resolution will be
about half of either. You will also be measuring any effect of
defocusing. Photographic testing of lenses requires very rigid and
accurately made spcial cameras with absolutely flat and accurately
located focal plane. Actual testing is done on glass plates or with a
vacuum back. Nonetheless useful testing can be done with plain vanilla
cameras provided some care is excercised and you are knowledgible of
the possible errors.
You can also look at the aerial image. This is the image in "space"
using a very high quality magnifier to examine the image. The
magnifier goes about there the image would be focused. A low power
high quality microscope is ideal but not necessary. I've found that a
projection lens from an 8mm projector makes a pretty good magnifier
for LF lenses. Not enough magnification for medium and small format.
This will give you much higher resolution numbers than photography
but is subject to all sorts of observational errors. If the magnifier
is not large enough it may effectively stop down the lens making it
look better at large stops than it really is.
The chart should have some instructions with it. It is scaled to
that when placed a certain number of focal lengths from the lens the
resolution bars are direct reading. You must be careful when examining
the bars either on a negaive or directly that you don't get fooled by
false resolution, that is seeing more bars than are there. Sometimes
the dark and light bars will reverse.
The lens should be checked both at the center and toward the
margins. It shold be checked wide open and at smaller stops. Probably
two stops down and four stops down give you some idea of what is
happening. Some lenses will have their best performance in the center
of the field when wide open, none will be best away from the center
wide open, all will sharpen up as they are stopped down.
I wish I could recommend a good elementary text on the use of this
chart. Its possible that Edmund Scientific has a booklet, they sell
the charts. They have recently split up so finding things there is not
so easy as it was. They used to publish some very good booklets on
optics.
A good reasonably elementary book on photographic optics will be
helpful. Check your library to see if they have _Lenses in
Photography_, 2nd edition, Rudolf Kingslake This is long out of print
but is available used and the library may have it. It explains the
basic lens faults, or aberrations and gives some idea of what to look
for.
With a litte practice you can tell a lot about a lens by examining
its aerial image with simple equipment.
---
Richard Knoppow
Los Angeles, Ca.
[email protected]
From: Paul Butzi [email protected]
Newsgroups: rec.photo.equipment.large-format
Date: Thu, 12 Apr 2001
Subject: Re: Me too, me too, I want to do a lens test.
"annqlee" [email protected] wrote:
>It seems that it would be harder than I thought. Maybe I should leave it up >to a professional.No, no, no! Don't do that.
There are lots of tremendously useful things you can learn from
running your own lens tests, and in my not very humble opinion, the
LEAST important one is figuring out the resolution of your lenses.
If you do your own lens tests, you'll end up learning about:
* the difference between the center of the field and the edge,
* the difference between how lenses perform close up versus at infinity
* how rigid your camera is
* how rigid your tripod is, and the tripod head
* how much using a lens hood can improve contrast
* the difference between 'sharpness' and 'resolution'
* how much of a difference different films make
* perhaps how much of a difference different developers make
and that's by no means exhaustive.
Do some lens tests, if only for the learning experience of doing
them.
The downside is that you'll start obsessing about a whole new
list of details, like rigidity of tripod legs, or camera stiffness, or
film plane position. In the end those things can help you make
the photographs you want to make, but in the middle thinking
about them gets in the way.
-Paul--
http://www.butzi.net
From Leica Mailing List;
Date: Sat, 23 Jun 2001
From: Phil Stiles [email protected]
Subject: Re: [Leica] Resolution vs. Contrast?
A very interesting comparison. Back in the '60s we used to say the
German glass had the resolution, and the Japanese the contrast. The
"Leica look" was softer, but with more shadow detail. Photojournalists
were said to go for the "bright" images with Nikon (which is notorious
for needing to be stopped down.) This is enough dim memory, rumor and
innuendo for one day. I'll guess #1 is German and #2 Japanese. But like
the finish to wine, we know the proof of the pudding is in the Bokeh!
Thanks for posing this puzzle.
Phil Stiles NH USA
Peter Klein wrote:
> Folks: I'm currently comparing two older 85-90mm lenses, both > approximately f/2. To avoid prejudicing the discussion, I'm not going to > reveal what brand(s) they are. > > I shot the "newspaper taped to the wall" test with each. This means > shooting a double-page spread of the stock market quotes, with the camera > on a tripod, placed so the newspaper just fills the frame horizontally. I > shot Kodachrome 64 at all stops, and viewed the slides with a portable 30x > hand microscope. Please note that I'm taking some real pictures with the > lenses, too, but that roll isn't finished yet. > > All this is crude, but it does give a reasonable idea of how each lens > performs at that distance. The lower-case letters in a stock market \ quote > are about 1mm high, and you can see three distinct lines in them (such as > in the letter "e"). Reduce a 68 cm-wide double-page spread down to a 36 > mm-wide frame, a factor of 18.9, and these three lines in a mm-high letter > reduce to less than .0175 mm each on film. > > I encountered an interesting difference between the two lenses. Wide open, > lens #1 shows the smallest print quite blurred. But I can tell that the > characters are letters and numbers, and sometimes identify one. However, > the lines of the characters are very light and somewhat irregular in how > dark they are. In other words, the appearance of the print is very low > contrast. > > With Lens #2, wide open, the text is completely unreadable. The space > within individual characters seems almost completely filled in, such that a > small "e" looks like a dot and a capital "E" looks like a rectangle. But, > though the characters are blurred beyond recognition, the outer edges of > the characters are distinct, and the contrast between a character and the > space around it is much more distinct than Lens #1. In other words, Lens > #2's image appears to be of lower resolution, but higher contrast. > > Both lenses seem to have about equal resolving power at f/5.6 and narrower, > but Lens #2 continues to have the appearance of better contrast at these > openings. Oddly, at a couple of stops in this range, both lenses show > slightly more readable characters near the *edges* of the slide than in the > center! > > Now the fun part--which lens do you think might take better pictures > (especially wide open), and why? I'm curious how this crude but easily > done test translates to "look." > > --Peter
From Rollei Mailing List:
Date: Tue, 03 Jul 2001
From: Craig Maxwell [email protected]
Subject: Re: [Rollei] Tessar/Planar
Well for it's worth, a few months ago I tested the lenses on both my
Rolleiflex 3.5F Planar and my Rolleicord Vb. A tripod was setup with a
Rolleifix mount and each camera was mounted in turn and a roll of Fuji
Velvia color transparency film was exposed. The test subject was a
building in front of the camera which consisted of detailed woodwork, an
iron gate and both very bright (highlights) and dark areas (shadows). The
exposures were bracketed and the aperture settings were all around f8 -
f16. Each roll was processed and evaluated on a color corrected GTI
Lightbox. MUCH to my surprise, I could not find any differences in
sharpness using my eye and a 4X Schneider loop, either in the center of
the image or in the corners. Now PLEASE keep in mind, I'm not saying that
this was a definitive or scientific test, and I'm not claiming that the
respective lenses are identical, but the real world results proved to me
that when using the mid range of apertures on either camera I can expect
reasonably similar results and that my Rolleicord will be a perfect backup
camera to have when on an assignment using my 3.5F. In fact, I was not
even testing for image sharpness per se, but I was actually more
interested in the differences in color rendition and contrast between the
two lenses, which again to my eye were identical.
Regards,
Craig Maxwell
From Rollei Mailing List;
Date: Tue, 03 Jul 2001
From: S Dimitrov [email protected]
Subject: Re: [Rollei] Tessar/Planar
Within the range you describe, it is hard to tell. But try it wide open,
and that's when you start realizing that the extra cost of the
Planar/Xenotar is well justified. All the f-stops are usable, not just
the mid range. An important issue when one tries to use the full
capabilities of a piece of gear.
Slobodan Dimitrov
From Rollei Mailing List;
Date: Wed, 4 Jul 2001
From: [email protected]
Subject: Re: Re: [Rollei] Tessar/Planar
My experimental procedure and results were almost identical to those
described by Craig to compare his Planar and Xenar, with almost the same
results. There was, however, a slight difference in color cast between
the two, with the Planar rendering more "neutral" compared with a touch of
blue in the Xenar tsps, entirely acceptable to my eye. My test film was
Provia, which I believe more capable of showing nuances of color than
Velvia. That might explain Craig's color rendition results.
Comparing sharpness and contrast, both lenses are excellent, difficult to
impossible to tell apart. After some years of practical use, I believe
there are "character" differences between the lenses that I can't describe
or quantify (and could be in my mind, as far as I know). But these are
nuances, at best, and I use the cameras interchangeably, for the most
part.
s Slobodan points out, the Planar is superior at wider apertures, but that
is of little practical importance to me because when my Rolleis are on a
tripod, I never use f stops wider than f8, and when forced to use lenses
wide open, it is always hand-held under conditions of low light and slow
shutter speed where sharpness is going to be compromised by several
factors. The Xenar performs well enough under those circumstances.
My cameras are a 3.5F (the best) and an MX-EVS (my favorite). I love them
both.
Allen Zak
Date: 27 Jun 2001
From: [email protected] (john chapman)
Newsgroups: rec.photo.equipment.35mm
Subject: Re: SQF Testing - was Re: Pop Photo tests Tamron 24-135
I have followed the lens tests initiated by Herb Keppler while at
Modern Photography, and reestablished at POP when he moved there after
leaving MP. I certainly consider the tests, but have found the SQF
stuff much less reliable as a measure of lens quality than the far
simpler LPM. I have bought several lenses based on POP's high rating
(SQF and comments) only to discard the lenses because of poor
performance. Several examples include the Tokina 19-35 (cheap
version), Tokina 20-35/2.8, and the Sigma 170-500. My Series I
Vivitar 19-35, which POP did highly rate, and which I consider one of
the all time best buys in lenses, was optically superior to both
Tokinas. POP rated the 20-35/2.8 as an excellent pro quality lens.
Incidently, I bought and tested two samples of the Tokina 20-35/2.8
because the first one was so mediocre I thought it might be simply a
bad sample. Because of better construction and slightly better
optical performance at the edges, I ultimately bought the Nikon
20-35/2.8 to replace the Vivitar, but I will always have a warm
feeling for that lens and never hesitate to recommend the lens to
those on a tight budget who need wide angles. I have since replaced
the Nikon with the 17-35/2.8.
Believing that high LPM is an absolutely necessary (while accepting
not fully sufficient) condition of quality, I shoot (using the Modern
Photography lens testing kit) resolution test targets on TMAX 100. I
do not attempt to measure curvature of field since it is irrelevant to
me whether a lenses has inherent poor edge resolution, or high
curvature of field. However, I recognize that in senics high
curvature of field would likely not be noticed. While I could convert
my results to LPM figures, it is easier for me that all lenses are
compared to the results obtainable with my Nikon 50/1.4 MF, which is
probably my sharpest lens. Lenses that don't make the grade are sold,
regardless of what ratings others give them.
Since I will inevitably be in situations where I will have to use the
lenses at the widest aperatures, I only test at the 3 widest
apertures. If they don't hack it there, out they go. Of course, I
try to shoot at the smallest apertures that light and subject allow.
Actually, I have only found one lens where stopping down from 2.8 to 4
decreased resolution (Nikon 80-200/2.8 dual control).
I used to test only using MF, but as I have gotten older, it has
become problematic whether this is more reliable for me than AF. When
using MF I will generally use focusing magnifiers. However, the more
such aids I use the further away I get from real life shooting. And,
of course, I am trying to determine the lens' real shooting quality in
my hands (and eyes), in addition to its maximum capability.
Over the last 5 years or so I have bought, borrowed and tested perhaps
30-40 lenses. Besides test targets, a few scenics are also shot using
slide film with each lens. The results are evaluated using loupes of
8x, 15X, 22X, and 30X loupes. I have yet to find inconsistences
between my test target results and the slides (real pictures), which
is more than I can say with regard to POP's SQF.
Bill Tuthill [email protected] wrote
> Thanks to Tony Polson for pointing out that Amateur Photographer > (as he didn't correct my "UK magazine" remark I suppose that's true) > tests both high and low contrast targets. However even at low contrast > the Tamron 24-135 resolved 65-92 lp/mm, better than the 43-78 lp/mm > that Pop Photo found. Perhaps Pop Photo testers forgot to focus? ;-) > More likely Amateur Photographer tests with Tech Pan, not TMX. > > VT [email protected] wrote: > > > > - but what grade do you accept as good enough? A+, A, B+, B, C? > > Depends on the lens. If I didn't already own a broken Sigma lens, > I might buy a Sigma 28-105/3.8-5.6 for its light weight, because it > achieved an SQF score of B+ at 105mm f/11. However I would not buy > the Sigma 28-135/3.8-5.6 because at 135mm it did no better than C+ > at any f-stop. Of course sample variation makes these scores suspect. > > > For example the dreaded Vivitar Series 1 (aka Cosina) 19-35mm actually > > manages to get A and B+ ratings at its optimum apertures at all the > > tested focal lengths for 17x and 22x enlargements - (don't get me wrong - > > I own this lens - and I would tend to agree with the rating - but many, > > many would not - considering the lens to be pretty close to rubbish) > > If you know what f-stop you need to get A or B+ enlargements, and don't > have to work quickly, then the lens is useful for you. > > Likewise, the Minolta e-group often denigrates my 70-210/3.5-4.5, which > I bought instead of the revered 70-210/4 for light weight and fast AF. > Photodo testing shows my lens to have better MTF scores at 210 f/8 than > the far more expensive Minolta 80-200/2.8 G at 200 f/8. My tests also > show improved sharpness at f/8, so I often use A mode to get f/8. > > >>Yes, but note how wildly MTF numbers vary, so they don't seem particularly > >>objective either. For instance, Amateur Photographer (UK?) tested the > >>new Tamron 24-135 as having 90-122 lp/mm center resolution at full zoom, > >>whereas Pop Photo tested it as having only 43-78 lp/mm center resolution. > >>That is quite a difference!!! > > > > Well, that's "sample variation" for you! > > Given Tamron's quality control on their SP (luxury) lenses, I doubt > this can be explained by sample variation. It is more likely to be > one of the things I mentioned in paragraph 1. > > (You're right about my misuse of MTF, thanks for the correction.) >> > Since SQF is a combination of Pop Photo's testing procedures and > > "Subjective" assessment - The S in SQF - is actually "Subjective" > > Yes, but what better measure is there to describe lens qualities that > lead to great enlargements?
Date: 27 Jun 2001
From: [email protected] (dan)
Newsgroups: rec.photo.equipment.35mm
Subject: FYI: PopPhoto tests available by mail
I saw this info posted on the EOS list (thanks JL)
and thought some of y'all might be interested.
There does not seem to be any indication of wether or not
these copies are in colour or b&w.
PopPhoto's Camera Test Index
http://popphoto.com/Film/PrintArticle.asp?ArticleID=38
PopPhoto's Lens Test Index
http://popphoto.com/Film/PrintArticle.asp?ArticleID=39
"For a copy of any of these lens test reports, please send a stamped,
self-addressed envelope (#10 size for up to three lens tests, 6.5x9.5
inches or larger for more than three lens tests or for a camera test)
to: Test Reports, Popular Photography, 1633 Broadway, New York, NY
10019. Please enclose check or money order (made out to Popular
Photography) for $2 for each lens test, $5 for each camera test
requested. Allow eight weeks for response."
May the Light be with you.
-----
dan
Date: 28 Jun 2001
From: [email protected] (john chapman)
Newsgroups: rec.photo.equipment.35mm
Subject: Re: SQF Testing - was Re: Pop Photo tests Tamron 24-135
I am, I believe, like you in considering SQF as having value, but
remain a bit cynical about it. I think POP would do best if they
continued to use LPM readings along with their SQF rating. POP could
also publish examples of what they deem the different SQF levels
represent. When POP tests films, they generally show a tightly
cropped image of an eye with eyelashes to show the differences between
films. They could do something similar showing the eye/eyelashes at
each of the SQF levels at each of the different enlargments. This
would help quantify what they mean when they say B+, and let the
reader determine what levels are adequate for their needs.
It is possible that the poor samples have led people to their low
opinion of the Vivitar/Phoenix/Cosina 19-35. It is plausible that
inexpensive lenses are simply not subjected to the same quality
control as expensive ones. On the other hand, I more suspect they
despise the lens because of its price and somewhat flimsy looking
construction rather than its optical performance, which I found to be
excellent. Although I am not sure its construction is any worse than
the plastic consumer grade lenses that Nikon and Canon put out. I now
regret selling mine since there are times where rain and dust
conditions are so bad I would prefer not risking my 17-35 Nikon. If I
can ever find a used one cheap on ebay or wherever I will probably buy
it.
I have seldom ever encountered other than rave notices about Tokina
lenses, which rival and exceed OEM lenses in terms of rugged
construction. On the other hand, the more than half dozen or so that
I have owned were most were very mediocre or worse optically. Again,
a lens may do many things well but if it cannot adequately resolve all
those little LPMs, then it fails the most basic test.
These two examples are the reasons that I discount most peoples'
opinions about lens quality -- and even the opinions of POP's lens
testers.
Incidently, another phenomenon that I have encountered is, that with
the really good lenses, the sharpness (contrast and resolution) of the
lens remains high even when focus is not absolutely precise (focusing
manually or with AF is not always the most precise). Whereas, with a
poor or mediocre lens sharpness seems to fall off much more rapidly as
focus becomes less precise. There is absolutely no way for me to
quantify or even explain this observation, but I am convinced of its
truth. I would be interested if others have had a similar experience.
...
Date: Wed, 25 Jul 2001
From: Bill Tuthill [email protected]
Newsgroups: rec.photo.equipment.35mm
Subject: Lens Comparison Table
Several people asked me to post this. Note that columns are separated
by tabs, and line width is greater than 80.
focal length & speed wgt len cost close filter EZavg Photodo
Canon 17-35/2.8 L USM 545g 98mm $1300 42cm =F877 3.26 3.2
Canon 20-35/3.5-4.5 USM 340g 83mm $450 30cm =F877 3.12 3.4
Canon 22-55/4.0-5.6 USM 175g 59mm $130 35cm =F858 2.24 2.8
Canon 24mm f2.8 fixed 270g 49mm $329 25cm =F858 3.75 3.9
Canon 24-85/3.5-4.5 USM 380g 70mm $290 50cm =F867 2.60 3.1
Canon 28mm f1.8 fixed 310g 56mm $430 25cm =F858 3.55 3.2
Canon 28mm f2.8 fixed 185g 43mm $185 30cm =F852 3.82 3.8
Canon 28-70/2.8 USM L 880g 118mm $1050 50cm =F877 4.01 3.9
Canon 28-80/3.5-5.6 USM 200g 71mm $150 38cm =F858 2.96 2.2
Canon 28-105/3.5-4.5 USM 372g 75mm $220 50cm =F858 2.94 3.3
Canon 28-135/3.5-5.6 IS USM 500g 79mm $470 50cm =F872 3.21 3.5
Canon 28-200/3.5-5.6 USM 500g 89mm $500 45cm =F872 2.42 ?
Canon 35-350/3.5-5.6 L 1480g 167mm $1530 60cm =F872 2.87 3.3
Canon 50-200/3.5-4.5 L 695g 146mm used 120cm =F858 ? 3.7
Canon 55-200/4.5-5.6 USM 310g 97mm $190 120cm =F852 2.31 3.0
Canon 50mm f1.4 fixed 290g 51mm $350 45cm =F858 3.96 4.4
Canon 50mm f1.8 fixed 130g 41mm $85 45cm =F852 3.91 4.2
Canon 70-200/2.8L USM trpd 1275g 194mm $1180 150cm =F877 4.06 4.1
Canon 70-200/4.0L USM 705g 172mm $900 120cm =F867 4 ? 4.1
Canon 70-210/3.5-4.5 USM 550g 122mm used 120cm =F858 3.12 3.1
Canon 75-300/4-5.6 USM 495g 122mm $210 150cm =F858 2.58 3.1
Canon 75-300/4-5.6 IS USM 650g 138mm $475 150cm =F858 2.59 2.9
Canon 85mm f1.8 USM 425g 72mm $345 85cm =F858 4.52 4.1
Canon 100-300/4.5-5.6 USM 540g 121mm $270 150cm =F858 2.65 2.4
Canon 100-300/5.6 L USM 695g 167mm $560 140cm =F858 3.05 3.6
Canon 100-400/4.5-5.6 L IS 1360g 189mm $1650 180cm =F877 3.86 3.6
Canon 200mm f2.8 L USM 765g 136mm $670 150cm =F872 4.41 4.1
Canon 300mm f4.0 L USM 1220g 214mm $930 250cm =F877 4.34 4.3
Canon 300mm f4.0 L IS USM 1190g 221mm $1229 150cm =F877 4.04 3.4
Canon 400mm f5.6 L USM 1250g 257mm $1074 350cm =F877 3.32 3.4
Canon 400mm f5.6 L USM 1250g 257mm $1074 350cm =F877 3.32 ?
Canon 400mm f4.0 DO IS USM 1930g 233mm $2500 cm =F8 ? ?
Canon 400mm f2.8 L USM 5910g 348mm $6200 400cm =F848 4.60 4.4
Canon 400mm f2.8 L IS USM 5207g 308mm $8700 290cm =F852 ? 4.4
Canon macro 50/2.5 1:1 280g 63mm $285 23cm =F852 4.34 4.4
Canon macro 100/2.8 1:1 650g 105mm $430 30cm =F852 4.57 ?
Canon macro 100/2.8 1:1 USM 600g 119mm $600 15cm =F858 ? ?
Canon macro 180/3.5 1:1 USM 1090g 187mm $1289 48cm =F872 4.20 3.9
Rebel2000 1.5fps body 335g 90mm $250 DOF preview
Elan IIe 2.5fps body 580g 105mm $390 eye selected DOF preview
Elan 7e 3.5 fps body 575g 103mm $540 7 AF points
A2/A2e/EOS-5 3fps body 675g 121mm $500 soon to be replaced
EOS-3 4-7fps body 780g 119mm $1400 45 focus points
Contax 28-70/3.5-4.5 325g 68mm $630 50 M30 77
Aria body 3fps 460g 91mm $589 DOF preview
Minolta 17-35/3.5 G const 594g 150mm $1600 30cm =F877 3.07 3.3
Minolta 20-35/3.5-4.5 325g 78mm $430 ? =F872 2.76 2.8
Minolta 24mm f2.8 fixed 215g 69mm $340 25cm =F855 3.22 3.4
Minolta 24-50/4.0 const 285g 60mm $360 33cm =F855 3.68
Minolta 24-50/4.0 const 285g 60mm $360 33cm =F855 3.68 3.4
Minolta 24-85/3.5-4.5 415g 70mm $400 50cm =F862 3.26 3.5
Minolta 24-105/3.5-4.5 D 395g 69mm $400 46cm =F862 3.21 ?
Minolta 28mm f2.0 fixed 285g 50mm $550 30cm =F855 3.68 4.1
Minolta 28mm f2.8 fixed 185g 65mm $190 30cm =F849 3.00 3.8
Minolta 28-70/2.8 G 748g 120mm $1000 70cm =F872 3.87 3.7
Minolta 28-80/3.5-5.6 249g 69mm $110 38cm =F862 2.58 2.7
Minolta 28-85/3.5-4.5 490g 90mm $315 80 M25 =F855 2.99 ?
Minolta 28-105/3.5-4.5 485g 80mm $300 60cm =F862 2.85 2.7
Minolta 28-135/4.0-4.5 770g 109mm used 152cm =F872 3.21 3.6
Minolta 35mm f1.4 fixed 470g 80mm $1060 30cm =F855 3.50 3.8
Minolta 35mm f2.0 fixed 238g 50mm $278 30cm =F855 3.45 4.0
Minolta 35-70/3.5-4.5 220g 63mm $70 50cm =F849 ? 3.5
Minolta 35-105/3.5-4.5 495g 87mm used 150 M41 =F855 ? 2.8
Minolta 35-200/4.5-5.6 xi 500g 90mm used 39cm =F862 ??
Minolta 50mm f1.4 fixed 235g 40mm $230 45cm =F855 3.73 4.4
Minolta 50mm f1.7 fixed 170g 40mm $80 45cm =F849 3.19 ?
Minolta 70-210/4.5-5.6 new 370g 93mm $130 110cm =F849 2.85 ?
Minolta 70-210/4.5-5.6 new 370g 93mm $130 110cm =F849 2.85 2.7
Minolta 70-210/3.5-4.5 var 420g 100mm used 110cm =F855 2.90 2.9
Minolta 70-210/4.0 const 690g 152mm used 110cm =F855 3.09 ?
Minolta 75-300/4.5-5.6 525g 122mm $210 150cm =F855 3.04 2.6
Minolta 80-200/2.8 APO G trpd 1281g 170mm $1250 180cm =F872 4.18 3.9
Minolta 85mm f1.4 G fixed D 550g 70mm $670 85cm =F872 4.22 3.9
Minolta 100mm f2.0 fixed 480g 80mm $450 101cm =F855 4.60 4.4
Minolta 100-300/4.5-5.6 APO D 436g 102mm $450 150cm =F855 3.09 3.2
Minolta 100-400/4.5-6.7 APO 840g 149mm $700 200cm =F872 3.38 3.2
Minolta 135mm f2.8 fixed 356g 83mm used 100cm =F855 ? 3.6
Minolta 200mm f2.8 APO G 790g 130mm $900 150cm =F872 4.50 4.1
Minolta 300mm f4.0 APO G 1350g 220mm $999 250cm intg 4.09 3.4
Minolta 400mm f4.5 APO G 1920g 273mm $1900 300cm intg 3.77 4.0
Minolta macro 50mm f2.8 1:1 315g 55mm $350 20cm =F855 4.35 4.5
Minolta macro 100mm f2.8 1:1 D 510g 98mm $580 35cm =F855 4.22 4.5
Minolta macro 200mm f4 1:1 APO 1132g 195mm $1350 51cm =F872 ? ?
Minolta teleconverter 1.4 APO 175g 21mm $375 - - - -
Minolta teleconverter 2x APO 211g 43mm $380 - - - -
505/HTsi+ 2fps body 350g 89mm $275 no DOF preview
505s/XTsi 2fps body 414g 89mm $350 no DOF preview
5/aSweet2 3fps body 335g 87mm ? DOF preview
600si 2.1fps body 524g 98mm $420 DOF preview
800si 3 fps body 628g 107mm $460 DOF, 4 AF sensors
Maxxum 7 3.7fps body 575g 98mm $650 DOF, 9 AF sensors
Maxxum 9 4.5fps body 910g 111mm $1500 weatherproof
Ti Maxxum 9 updt body 790g 111mm ? weatherproof
RD6000 3 fps digital ? ? $6500 6 Mpix 64MB buffer
Nikon 20-35/2.8 IF D 585g 94mm $1400 50cm =F877 3.47 3.6
Nikon 24-50/3.3-4.5 D 365g mm $330 60 M50 =F862 3.49 3.2
Nikon 24-85/2.8-4.0 D 561g 78mm $620 49 M22 =F872 ? ?
Nikon 24-120/3.5-5.6 D 555g 80mm $480 50cm =F872 2.79 2.3
Nikon 28-70/3.5-4.5 D 355g 71mm $310 50 M39 =F852 3.27 2.8
Nikon 28-70/2.8 ED AFS 936g 127mm $1500 70 M50 =F877 3.97 3.7
Nikon 28-80/3.5-5.6 D 220g 69mm $160 50cm =F858 3.04 3.0
Nikon 28-105/3.5-4.5 D 476g 91mm $320 50 M22 =F862 3.41 3.2
Nikon 28-200/3.5-5.6 D 555g 95mm $440 200M85 =F872 2.69 2.6
Nikon 35-70/2.8 ED bargain 675g 95mm $625 60cm =F862 4.11 3.8
Nikon 35-105/3.5-4.5 D 410g 73mm $310 85cm =F852 3.02 2.9
Nikon 50mm f1.4 D fixed 225g 43mm $250 45cm =F852 3.98 4.2
Nikon 50mm f1.8 fixed 156g 39mm $95 45cm =F852 4.19 4.4
Nikon 70-210/4.0-5.6 D 590g 108mm $290 150M120 =F862 2.95 2.8
Nikon 70-300/4.0-5.6 ED 515g 74mm $300 150cm =F862 2.83 2.4
Nikon 75-240/4.5-5.6 D 413g mm $130 150cm =F852 2.53 2.1
Nikon 75-300/4.5-5.6 ED 850g 166mm used 150cm =F862 ? 3.2
Nikon 80-200/4.5-5.6 D 330g 88mm used 150cm =F852 2.72 3.1
Nikon 80-200/2.8 ED trpd 1301g 188mm $850 180M150 =F877 4.16 4.0
Nikon 80-400/4.5-5.6 VR 1304g 264mm $1700 230cm =F877 ? ?
Nikon 180mm f2.8 ED 750g 144mm $800 150cm =F872 3.92 3.6
Nikon 300mm f4.0 ED IF 1330g 219mm $800 250cm =F839? 3.94 3.7
Nikon macro 70-180/4.5-5.6 D 989g 167mm $760 37cm =F862 3.70 ?
Nikon macro 60mm f2.8 D 1:1 455g 75mm $330 22cm =F862 4.63 4.2
Nikon macro 105mm f2.8 D 1:1 555g 104mm $540 31cm =F852 4.54 3.9
Nikon ?fps N60 body 575g 96mm $300 barren of features
Nikon 2.5fps N65 body 394g 99mm $290 no ISO but DOF preview
Nikon 3.1fps N70 body 584g 104mm $430 no DOF preview!
Nikon 2.5fps N80 body 515g 99mm $480 5 AF points DOF preview
Nikon 4.1fps N90s body 754g 106mm $690 single AF zone
Nikon 4.5fps F100 body 780g 113mm $1299 5 selectable AF zones
Nikon mech FM3A body 570g
Pentax 24-90mm f3.5-4.5 355g 75mm $400 50cm =F867 ? ?
Pentax 28-70mm f4.0 AL 238g 64mm $180 39cm =F852 ? 3.3
Pentax 28-70mm f2.8 ED 800g 104mm $1080 43cm =F867 3.87 ?
Pentax 28-80mm f3.5-5.6 275g 78mm $140 50cm =F858 2.33 2.0
Pentax 28-105mm f4.0-5.6 FA 445g 96mm $325 43cm =F858 3.38 3.2
Pentax 50mm f1.4 fixed 220g 37mm $185 45cm =F849 ? 4.2
Pentax 50mm f1.7 fixed 170g 37mm $140 45cm =F849 4.13 4.4
Pentax 135mm f2.8 fixed 375g 80mm $350 70cm =F852 ? 3.5
Pentax 70-200 f4.0-5.6 FA 465g 117mm $250 110cm =F849 2.85 2.9
Pentax 80-200mm f2.8 ED trpd 1507g 192mm $1675 140cm =F877 3.67 3.2
Pentax 80-320mm f4.5-5.6 FA 550g 129mm $250 150cm =F858 3.01 2.5
Pentax 100-300mm f4.5-5.6 FA 605g 146mm $350 150cm =F858 2.85 2.4
Pentax 250-600mm f/5.6 F ED 5400g 440mm $7057 350cm =F843 ? ?
Pentax 300mm f4.5 ED IF 935g 160mm $780 200cm =F867 4.05 4.0
Pentax macro 50mm f2.8 FA 1:1 385g 70mm $355 19.5cm =F852 3.62 4.6
Pentax macro 100mm f3.5 FA 1:1 220g 72mm $200 43cm =F849 3.39 3.7
Pentax macro 100mm f2.8 FA 1:1 600g 104mm $560 31cm =F858 3.90 3.9
Pentax macro 200mm f4 FA 1:1 g mm $1350 cm =F867
Pentax ZN-50 body 345g 90mm $200 lens-incompatible
Pentax ZN-10 body 365g 90mm $300 no DOF preview
Pentax ZN-5n body 410g 90mm $360 DOF preview
Pentax PZ-1p body 650h 96mm $509 4 fps, hypermode
Sigma 17-35/2.8-4.0 EX 400g 83mm $479 50cm =F882 2.94 3.1
Sigma 24-70/3.5-5.6 old 263g 63mm $159 50cm =F855 2.88 2.2
Sigma 24-70/3.5-5.6 new HF 285g 76mm $ 40cm =F862 ? ?
Sigma 24-70/2.8 EX DF 700g 116mm $379 40cm =F882 ? ?
Sigma 28-70/2.8-4.0 old 286g 64mm $130 50cm =F855 2.62 2.9
Sigma 28-70/2.8 EX DF 645g 101mm $340 40cm =F877 3.24? 3.5
Sigma 28-80/3.5-5.6 macro 255g 69mm $79 50 M24 =F855 2.71 2.7
Sigma 28-80/3.5-5.6 macro HF 255g 71mm $89 50 M24 =F855 ? ?
Sigma 28-105/4.0-5.6 UC2 340g 71mm $99 50cm =F858 2.33 2.1
Sigma 28-105/3.8-5.6 UC3 275g 71mm $109 50cm =F862 ? ?
Sigma 28-105/2.8-4.0 soft 374g 81mm $199 50cm =F872 2.36 2.4
Sigma 28-135/3.8-5.6 DLIF 410g 75mm $189 50 M24 =F862 ??
Sigma 28-200/3.5-5.6 DLIF 515g 86mm $239 50cm =F872 2.10 2.7
Sigma 28-300/3.5-5.6 DLIF 580g 95mm $399 90cm =F872 1.87 2.7
Sigma 50-500/4.0-6.3 EX 1850g 216mm $999 100cm =F886 3.25 ?
Sigma 70-200/2.8 APO trpd 1390g 181mm $869 180cm =F877 4.05 3.9
Sigma 70-210/4.0-5.6 UC2 336g 84mm $118 120cm =F855 ? 2.1
Sigma 70-210/3.5-4.5 APO 601g 117mm $285 180 M75 =F858 3.44 good
Sigma 70-300/4.0-5.6 DL 589g 116mm $199 150 M95 =F858 2.17 2.9
Sigma 70-300/4.0-5.6 APO 584g 116mm $319 150 M95 =F858 2.60 3.1
Sigma 100-300/4.5-6.7 DL 422g 99mm $139 200cm =F855 2.29 2.6
Sigma 100-300/4.0 EX IF 1480g 224mm $799 180cm =F882 ? ?
Sigma 135-400/4.5-5.6 APO 1208g 181mm $549 200cm =F877 2.83 2.6
Sigma 170-500/5.0-6.3 APO 1315g 228mm $669 290cm 86C 2.87 ?
Sigma 300mm f4.0 APO macro 1335g 193mm $606 120cm =F877 3.74 ?
Sigma 400mm f5.6 APO macro 1445g 256mm $659 160cm =F877 3.51 3.5
Sigma macro 50mm f2.8 EX 1:1 358g 63mm $259 19cm =F852 4.70 4.2
Sigma macro 105mm f2.8 EX 1:1 451g 94mm $389 31cm =F858 4.48 4.1
Sigma macro 180mm f3.5 EX 1:1 1120g 180mm $799 46cm =F872 ? ?
Tamron 20-40/2.7-3.5 525g 81mm $669 50cm =F877 2.78 3.7
Tamron 24-70/3.3-5.6 270g 60mm $219 40cm =F862 2.30 ?
Tamron 24-135/3.5-5.6 530g 81mm $419 40cm =F872 3.65 ?
Tamron 28-80/3.5-5.6 237g 71mm $109 70cm =F858 2.38 3.0
Tamron 28-105/4.0-5.6 287g 78mm $190 50cm =F862 2.47 2.3
Tamron 28-105/2.8 LD 869g 112mm $799 49cm =F882 3.32 2.4
Tamron 28-200/3.8-5.6 LD 465g 82mm $299 80cm =F872 2.46 2.7
Tamron 28-200/3.8-5.6 LD 2 490g 85mm $310 49cm =F872 2.89 ?
Tamron 28-200/3.8-5.6 LD XR 354g 71mm $329 49cm =F862 ? ?
Tamron 28-300/3.5-6.3 LD 570g 94mm $499 82cm =F872 2.22 2.6
Tamron 70-210/2.8 LD trpd 1340g 177mm $899 150cm =F877 3.15 3.4
Tamron 70-210/3.5 SP MF! 869g 155mm $374 cm =F862 ? ?
Tamron 70-300/4.0-5.6 LD 510g 116mm $249 150cm =F858 2.83 2.4
Tamron 70-300/4.0-5.6 LD 1:2 435g 117mm $325 150 M95 =F862 2.83? 2.4?
Tamron 80-210/4.5-5.6 old 281g 98mm $119 150cm =F852 2.40 2.2
Tamron 100-300/5-6.3 old 354g 116mm $150 150cm =F855
Tamron 200-400/5.6 soft LD 1210g 178mm $539 250cm =F877 2.18 1.2
Tamron 300mm f2.8 LD IF 2247g 217mm $2613 250cm =F8112 3.60 2.8
Tamron macro 90mm f2.8 1:1 403g 97mm $360 29cm =F855 4.26 4.3
Tokina 19-35/3.5-4.5 193 390g 80mm $200 40cm =F877 2.71 3.3
Tokina 20-35/2.8 ATX 235 585g 86mm $700 50cm =F877 3.07 2.5
Tokina 24-200/3.5-5.6 ATX 760g 89mm $310 80cm =F872 3.20 ?
Tokina 28-70/2.6-2.8 ATX 760g 110mm $439 70cm =F877 3.63 3.1
Tokina 28-80/2.8 ATX 280 810g 120mm $599 50cm =F877 ? ?
Tokina 28-105/3.5-4.5 new 420g 75mm $189 45cm =F862 2.94 2.7
Tokina 60-300/4.5-5.6 685g 120mm used 200M150 =F858 ? ?
Tokina 80-200/2.8 ATX trpd 1350g 184mm $760 180cm =F877 3.28 3.4
Tokina 100-300/4.0 ATX trpd 1540g 230mm $720 200cm =F877 3.03 3.1
Tokina 80-400/4.5-5.6 ATX 960g 136mm $549 250cm =F872 2.32 2.3
Tokina 300mm f4.0 ATX IF 1140g 187mm $600 200cm =F877 3.57 ?
Tokina 400mm f5.6 ATX IF? 990g 202mm $440 240m =F872 2.80 2.8
Tokina macro 100mm f2.8 1:1 550g 98mm $370 35cm =F855 3.92 3.9
Vivitar 28-105/4.0-5.6 old 360g 72mm $170 50cm =F858 ? ?
Vivitar 70-210/2.8-4.0 ser1 709g 181mm $270 110cm =F862 3.28 3.0
Vivitar 70-300/4.2-5.8 old ?g ?mm used ?cm ? ? 3.1
Vivitar 70-300/4.5-5.6 ser1 565g 152mm $160 150cm =F862 ? 2.3 ?
Vivitar 100-400/4.5-6.7 ser1 733g ? $250 198cm =F867 ? 1.2
Vivitar macro 100mm f3.5 270g 71mm $140 43cm =F849 3.39 3.2
Voigtlr macro 125mm f2.5 1:1 690g 88mm $ 38cm =F858 ? ?
Date: Fri, 27 Jul 2001
From: Bill Tuthill [email protected]
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Lens Comparison Table
Tony Polson [email protected] wrote:
> A tremendous oeuvre and a useful resource. Thanks for posting it.
You're welcome.
By the way, I should have said that the column header "EZavg" represents
the grade from http://photozone.de/easytxt.htm (a composite of magazine
review scores).
Date: Sun, 05 Aug 2001
From: Paul Chefurka [email protected]
Newsgroups: rec.photo.equipment.35mm
Subject: More Leica/Nikon lens tests
I think I have a masochistic streak in me somewhere...
Given all the interest and input I got from last weekend's set of lens
tests. I redid them this weekend.
I tried to address the most common objections I heard last week. The
test methodology has been substantially improved, and I included tests
at f/2.0 as well as 4.0 and 8.0. Additional Nikkor lenses were added
(a 35, another 50 and an 85 - all AF-D). The test objectives are
still sharply limited.
http://members.home.net/chefurka/Photo/LensTests2/LensTests2.html
Have fun.
Paul Chefurka
Date: 02 Aug 2001
From: [email protected] (ShadCat11)
Newsgroups: rec.photo.equipment.35mm
Subject: Re: blind tests again ;-) Re: Some lens tests (Leica, Nikon and CV)
Mike Lipphardt [email protected] wrote:
> I think Paul's tests were rather well done. They very clearly showed the > differences between lenses on the subject and at the distance he chose, > using the same stop and films. He also specified those conditions. There > isn't anything to question within the limitations of his test, and if you > want to pic nits, that's fine. He could have tried various distance and > fstop combinations for instance, but since the number of combinations is > enormous, I am not surprised he didn't.
I agree with Mike. Yesterday I thought Leica mystique was a load of BS,
but today I am a believer.
While I am a great admirer of Leica lenses, I don't think the above-
mentioned test was conclusive. It demonstrated the superiority of those
particular Leica lenses v. those particular Nikkor lenses under those test
conditions.
I have owned several samples of lenses from reputable makers which
performed differently one from another. Those included Nikkor 28 and 50
mm lenses and two samples of 90 mm Summicrons, and several samples of
Rollei and Hasselblad lenses. The differences were minor (in some cases,
not so), but noticeable.
Lens tests can be useful, but be careful to not place too much value on
them.
Allen Zak
Date: Tue, 15 May 2001
From: "bbb_bbb" bbb_bbb@bbb_bbb.ca
Newsgroups: rec.photo.darkroom,rec.photo.equipment.medium-format
Subject: Re: Asking for Help from MF Shooters & Printers
Clint Bailey wrote in message ...
>Especially now, >that most of the glass is designed by computer and also with the >majority of the quality control is also done by computer.
Clint,
QC is not "done by computers," at least for the better lenses. Go to the
"Virtual Tour of Lens Production" on the Zeiss website to see how modern
lenses are made:
http://www.zeiss.de/de/photo/home_e.nsf
As for your original question, I suggest that you simply trust your eyes.
Image quality is in the eye of the beholder (or the customer, if you are a
commercial photographer). You claim to be able to see a difference between
the two systems that you mention, yet you "would tend to agree with"
people who claim that there is no difference. In my case, I would trust my
own judgement over hearsay.
Bernard
Date: Sat, 16 Jun 2001
From: [email protected] (David S. Berger)
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Expensive f2.8s beaten by cheaper slower counterparts!
Elie:
Lens testing is simple, but it takes patience.
Take some pictures with different lenses. Use a variety of apertures,
different lighting conditions, etc. Process and print (at least 4x6,
8x10 would be better). Now, view the prints as you normally would
view them; in other words, not with a loupe. Which pictures LOOK
better? Lenses that produced better looking pictures are better
lenses, at least for the type of picture being viewed. You WILL find:
1) Sharpness, as measured with bench tests, is the least important
factor. It's not that sharpness itself is unimportant, it's just that
sharpness, as an optical problem, was solved long ago. That is, all
lenses are sharp. Thinks like contrast, color, flare control, shadow
and highlight detail (related to flare), out of focus rendition
(bokeh), and other factors are what distinguish lenses.
2) Lens from different manufacturer A can be better than a similar
lens from manufacturer B, for a given type of shot. For a different
type of shot, the lens from manfuacturer B can be better than that
from manufacturer A.
This is time consuming, but that's the way it goes. As you get more
experienced, try different films (different speeds, different makers,
slides). Some lenses perform better with some films that with others,
in my experience anyway.
hope this helps,
david
Elie A Shammas [email protected] wrote:
>so what would be a good way to test lenses? Please share your insight >with >us, I am eager to learn. >Thanks > >Elie
....
Date: 5 May 2001
From: [email protected] (Michael Gudzinowicz)
Newsgroups: rec.photo.equipment.35mm
Subject: Re: De-centering effects
me [email protected] wrote:
>What would be the effect of decentering of lens elements >(possibly caused by dropping the lens accidentally)? Would it >be visible in normal kind of pictures, or if not severe, would >it require a "brick-wall" type of test to show up?
It may be visible depending upon severity and if you know what
to look for.
The term refers to the alignment of glass elements in each group, and
group alignment. The centering is done at the factory when they finish
the edges of the elements, glue elements together, machine the lens
mounts, mount the glass, and assemble the groups. It is possible to
create a centering problem by dropping the lens in which case the
optical axis of one or more groups is no longer in alignment with the
others.
If you want to look for a centering problem directly, there are a
couple of approaches which require an improvised optical bench. Focus
the lens on a small bulb filament covered with foil with a pinhole in
it (star image), and rotate the lens. If the image moves around in a
small circle when viewed with a microscope, it is decentered. The
degree may/may not affect performance.
If the image shows coma on axis, you have a real centering problem.
The direction and size will remain the same across the field unlike
common coma which runs out radially from the lens axis.
If the star image is placed off-axis and the lens is rotated, its
orientation will vary and distance from the axis will increase and
decrease with rotation. Note that the image wander may not be present
if more than one surface is decentered permitting cancellation.
However, decentration coma may still be marked.
Another problem which will arise if the cells/groups/elements are off
axis, is that the plane of focus will no longer be perpendicular to
the lens axis - it will be tilted. This is fairly common if the lens
mount is damaged, or if the planarity between the film and camera's
lens mount is altered due to camera damage.
From Rollei Mailing List;
Date: Thu, 26 Apr 2001
From: Richard Knoppow [email protected]
Subject: Re: [Rollei] Introduction & Question
...
I suggest using strobe illumination when testing cameras. It gets rid of
motion bluring virtually completely. You may be surprized at how sharp a
lens turns out to be when tested with strobe.
----
Richard Knoppow
Los Angeles,Ca.
[email protected]
Date: Tue, 21 Aug 2001
From: "Peter A. Klein" <[email protected]>
Subject: [Leica] OM vs. Leica Lens tests, was How good/bad/terrible is the R4?
> The Olympus OM system also has a good reputation for macro work. The 50
> mm f/2 and 90 mm f/2 are reputed to be the equal of Leica glass. The 4T
> body is available (used) for about the same $$ as the Contax, and a "2"
> series for around $200. You could also pick up a 50 mm /f3.5 for $160,
> and get a 50 mm f/1.8 for another $30 for non-macro work. The 50 will
> get down to 1:2 on its own, and 1:1 with a 25 mm extension tube.
>
> See this site for a detailed OM lens tests:
>
> http://members.aol.com/olympusom/lenstests/default.htm
I'm glad someone mentioned Gary Reese's OM lens test site. While the site is largely devoted to lenses for the Olympus OM system, Gary has
several Leitz/Leica lenses on the site as comparisons. There's also a
few Nikkor, Canon, and Minolta and Pentax lenses. Kyle's favorite
bargain rangefinder (Canonet QL-17) is there, too, and it doesn't come
off badly.
Gary uses a large USGS topographic map of the Grand Canyon as the test
target at 1:40. The target has low-contrast as well as high-contrast
components. He evaluates the resulting slides on a good projector. The
result is a very consistent and real-world evaluation. He also shows
how the mirror and automatic diaphragm on an SLR significantly affect
picture quality.
Anyway, if you want to see how a few Leica lenses compared to the
others, check out Gary's site. He includes the 50mm Summicron-M and 90
APO Summicron-M, and the 28mm Elmarit-R and 90mm Summicron-R.
Of course, bokeh, "glow," "look," and Pride of Leica Ownership are not
included in the tests. :-)
- --Peter Klein
Seattle, WA
From Leica Topica Mailing List:
Date: Tue, 21 Aug 2001
From: Henning Wulff <[email protected]>
Subject: Re: [Leica] OM vs. Leica Lens tests, was How good/bad/terrible is the
R4?
Strange results, and testing, to say the least!
- --
* Henning J. Wulff
/|\ Wulff Photography & Design
/###\ mailto:[email protected]
|[ ]| http://www.archiphoto.com
From Leica Topica Mailing List:
Date: Wed, 22 Aug 2001
From: "Dan States" <[email protected]>
Subject: Re: [Leica] OM vs. Leica Lens tests, was How good/bad/terrible is the
R4?
So, do we really believe that the old Olympus 90 is as good or better than
the new APO-Summicron? For that matter, according to this site, the old
Summicron 90 R is nearly as good as the new APO. I own the R and while it is
fine for it's day, it sure as hell is not going to match the new APO.
According to the rating scale, a c rating indicates the performance is
unacceptable above 5x7 enlargment. Quite a suprise to many APO and non APO
users Im sure, as they will now realize that their lenses should not be used
at f2 for anything larger than a 5x. Jeepers, time to toss my slides.
Some of the Leica lenses are VERY old, and are being tested on Olympus
bodies.
While I agree from experience that some of the Olympus stuff was/is quite
good, it is a little far fetched to say they were/are at the top of the
game.
Sorry, but this is a test site that doesn't pass the test of good science.
Ahh, the internet, where myth and science are one...
Best wishes
Dan States
From: Martin Jangowski <[email protected]>
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Mamiya TLR Lens Question
Date: 19 Aug 2001
Roland <[email protected]> wrote:
> But I gather that Mamiya lenses might be an exception in being
> of higher resolving power. I'd be interested in a comparison between the
> Mamiya lenses and the Carl Zeiss lenses used on Hasselblads.
I made some informal tests with a 2.8/80 Planar (Rolleiflex E), a 2.8/80
Xenotar (Rolleiflex F) and a Mamiya 3.5/75 (Mamiya 6).
The Planar was very good, the Xenotar a little better (it was more contrasty,
sharpness is the same) and the Mamiya was best. However, the differences
are _really_ small. It may very well be that the Rollei lenses are at least as good as the Mamiya lenses, but the much better flatness of film in the
Mamiya aids greatly to get the best possible results.
For portraits the Planar is best, it has a very nice bokeh.
YMMV.
Martin
From Leica Mailing List:
Date: Wed, 22 Aug 2001
From: Mike Quinn <[email protected]>
Subject: [Leica] Re: Lens testing not useful?
Now if I can just get Erwin to give me his well-tested lenses....
The fact that I know (and sometimes remember) the characteristics of MY
LENSES at various apertures and lighting conditions is important to me.
I'd rather find out before I use them than after. I have enough other ways
to goof up. I prefer my equipment to be somewhat predictable.
Mike Quinn
From Leica Mailing List:
Date: Wed, 22 Aug 2001
From: Paul Chefurka <[email protected]>
Subject: RE: [Leica] OM vs. Leica Lens tests, was How good/bad/terrible is
the R4?
The one and only thing my recent foray into "lens testing" taught me is
that it's extremely hard (verging on the impossible) to get valid,
objective, defensible comparative results with the usual method of taking
a few pictures and examining them. As a result, I am now planning to
utterly disregard all "lens tests", whether published by persons unknown
on the internet, or in Pop Photo, or in books by camera system gurus.
The one and only thing that matters is whether a lens gives you results
you like. I understand full well the masculine lust to know whose is
sharpest (longest?), but in the final anaysis it's all crap. Stick the
lens on the camera, shoot for 6 months, and if you don't like what you're
getting try a different one.
And that result for the 90AA is a big fat clue that this test is as
untrustworthy as mine was.
Paul
From: "Bruce Wilson" [email protected] Newsgroups: rec.photo.equipment.35mm Subject: Re: Diffraction and B&W Date: Tue, 19 Feb 2002 The effects of diffraction are a photo that is a bit fuzzier (unsharp) than it can be. Most lenses have some aperture where it is sharpest, typically f/16 or f/22. Stop down smaller than that and you increase the depth of field (the hyperfocal distance) at the expense of overall image sharpness. Typically only those who shoot on a tripod worry about it (handheld shooters use the largest aperture possible and deal with camera shake as the biggest contribution to unsharp photos). A critical eye can see the difference between diffraction and shake easily (diffraction is unsharp in all directions, shake is usually blurred in only one direction,usually the vertical one). It's easy to test your lens to find the sharpest aperture, just keep track of your aperture for many shots of the same scene (use a tripod) and see which ones are sharpest. Colored fringes are what's known as chromatic aberration, and it is typically seen in poorer-quality wide-angle zoom lenses, near the outer edges when focused up close. All lenses are designed to focus properly using green light. Chromatically-corrected lenses (most lenses you can buy) add additional glass elements to correct for one other color of light. These work fine for most photography. Lenses marked 'apo' or 'apochromatic' are corrected for chromatic aberration of green plus two other colors. They are the best lenses to use if you are going to play with focal distance (like using macro lenses and tubes for close-up work). If you don't do macro work an apo lens won't do you much good (in fact, an apo lens, because it has more glass elements to generate reflections, can give poorer results than a simpler lens when focused near infinity; I still carry a simple chromatic-corrected four-element tessar-type lens for large-format shooting even thought I have a nice apo planar-type lens because the tessar is sharper when focused at infinity at f/16). This might be more than you wanted to know. -- Bruce Wilson http://chem.dynu.com/photo - "Ken Durling" [email protected] wrote... > Well, thanks folks. I feel better! ;-) Actually I wouldn't know > what diffratcion even looks like. I was imagining something like > color fringing, ergo my Q about B&W. Glad to hear it's not a real > big concern. > > > Ken
From: "Meryl Arbing" [email protected] Newsgroups: rec.photo.equipment.35mm Subject: Re: Lens testing realities - a bit shrill, but a good read. Date: Mon, 18 Mar 2002 There are a lot of people who think they can get $1000 worth of value out of a $100 lens and they are the same who tend to discount lens tests. In their effort to try and disprove tests which indicate that they have a collection of sub-standard optics they have a whole series of rationalizations. The most common misconception is "Lens Sample variation" where they claim that you can't trust any lens tests because you can never be sure if the "test" was one of the "good" ones or one of the "bad" ones. Well, the funny thing is that the idea of lens variation is only valid when you are talking about the cheap 3rd party manufacturers with poor quality control. All the best lens manufacturers (Zeiss, Leica. etc.) test 100% of their lenses and not just a sample. There is no variation to worry about. You can follow the entire lens production process on the Zeiss website ( http://www.zeiss.de )and even see the standard lens testing machines (K8 and K9 MTF testing machines) that Zeiss makes available to labs and repair facilities. Published lens tests may or may not be reliable if the manufacturer doesn't test every lens to make sure it is up to spec. For example, the published MTF curves for Zeiss lenses are done on actual production lenses while the published results from other manufacturers could be computer projections of idea rather than production lenses. Lens test sites such as Photo.do publish MTF charts based on their own testing. If there were actual lens variations then the MTF charts published by Zeiss and the independently calculated MTF charts on photo.do would show variation but they don't. Now, another myth that the anti-testers try to promote is that the individual photographer can make individual field tests of each and every lens that they consider buying with the idea that "I test my own lenses by using them and if I like it I keep it" It is strange that the author of this website goes on about "standardization" and yet there is no more non-standard approach. Lens defects such as poor resolution at the edges can be too easily hidden in DOF differences. Also, subjective tests are unreliable because of other factors such as the desire not to feel that they have bought a piece of crap. In fact, there is a simple way out of the lens testing dilemma. I just look for the name Zeiss and don't worry about whether I', getting a "lemon" or not...others will look for Leica...or Canon L series...etc. and forget the 3rd party compromise lenses where you have no idea what you are going to get. "Alan Browne" [email protected] wrote ... > http://cameraquest.com/lenstest.htm
From: Bill Tuthill [email protected] Newsgroups: rec.photo.equipment.35mm Subject: How do I test lens resolution? Date: Mon, 18 Mar 2002 Seems like I have three choices: 1. Buy the $10 home lens testing kit from http://bobatkins.com and follow directions contained therein. 2. On library microfilm, find the old Modern Photography article about lens testing and hope it tells me what to do. (I have seen this article in GIF files but they are hard to read.) 3. Figure out the equations on Norman Koren's website that map lens-to-subject distance into real resolution. I tried using the Koren2000 test charts, but forgot to measure distances. Comparing two zoom lenses, there were many distances! Anything else? If not, which of the above do people recommend? Thanks in advance.
From: Tony Polson [email protected] Newsgroups: rec.photo.equipment.35mm Subject: Re: How do I test lens resolution? Date: Mon, 18 Mar 2002 ...(quotes above post) Whichever you choose, there is no substitute for ALSO doing tests of your own within the range of subjects you intend to shoot. For viewing your test slides, there is no substitute for a good light box and a good loupe. For examining fine detail, most mid-price and some cheaper 6X and 8X loupes will be almost as useful as a Schneider or Rodenstock, even though they are often less-than-sharp at the edges, where they are also almost certain to show colour fringing. Just look through the optical centre.
From: "Meryl Arbing" [email protected] Newsgroups: rec.photo.equipment.35mm Subject: Re: Lens testing realities - a bit shrill, but a good read. Date: Tue, 19 Mar 2002 If you have a problem with whether Zeiss lenses are individually tested, perhaps you should take it up with Zeiss directly. They are quite open about it on their website such as when they say: Every lens tested over one hundred times In this way, Zeiss achieves 100% quality assurance, with every lens being tested exactly for more than 100 different criteria during its production. Carl Zeiss does not rely on statistical process control and/or spot inspection, like it has become the cost saving standard in mass producing industries. Zeiss rather performs a 100% quality control, like it is done for airplane components and other very demanding industrial products. In addition, some decades ago Carl Zeiss was the first lens manufacturer to publish MTF performance diagrams for its lenses. Several manufacturers have, in recent years, followed this example but with one decisive difference. The curve diagrams of Carl Zeiss show not just optimistic computer simulations, but the properties of lenses which have actually been built. They are not merely computer-generated curves which give no indication whatsoever of how good and uniformly the supplier manufactures this lens in volume production. www.zeiss.de "Tony Polson" [email protected] wrote... > "Mxsmanic" [email protected] wrote: > >"Paul Rubin" [email protected] wrote... > > > >> I'm skeptical that's true even for Zeiss > >> and Leica, but I don't use those lenses > >> and don't know. > > > >The last Zeiss lens I had contained a little sheet of paper in the box > >with the signature of the person who tested it. > > Unless you are talking about your Dad's Hasselblad, you have been > conned. Royally. > > The Carl Zeiss lenses for 35mm are all supplied with a signed test > certificate, but it is EMPHATICALLY NOT for the particular lens that > you bought. The only manufacturer of lenses for 35mm who has ever > done that was the original Angenieux.
[Ed. note: see Critical Focusing Issues pages for details...] From Rollei Mailing List: Date: Mon, 25 Mar 2002 From: Richard Urmonas [email protected] Subject: Re: [Rollei] Schneider - Zeiss debate > I recently got a early Vb and I did a quick comparison of resolving power > between this Xenar and the 6 element Planar of my 3.5E3. Nothing real > scientific but just a shot at f5.6 of my bookshelf at home. I can't see the > difference with a 10x loupe but after cutting it to "35mm" and fed to my > Canon FS4000 you can see some small differences. This Planar is really > amazingly sharp and this Xenar is close but just not as sharp as the > Planar. But then, there is more in life than resolving power. With this sort of test the focus becomes very critical. The viewing lens must exactly track the taking lens, and using a high power loupe to improve focus can have a large effect. Richard -- Richard Urmonas [email protected]
From: Tony Polson [email protected] Newsgroups: rec.photo.equipment.35mm Subject: Re: Leica fans won't like this.(May issue Popular Photography) Date: Sat, 21 Apr 2001 "Mike Lipphardt" [email protected] wrote: > Personally, I have found that anecdotal evidence is pretty useless. Unless > you can say what I just said - in other words, base your evaluation of the > lens on evidence, not opinion - then you have no real idea what you're > talking about. If only life were so simple. I really envy someone like you who can believe that lens performance can be expressed entirely on the basis of "evidence", by which I expect you meant a single performance index on the Photodo site, or even a "rating" that's an amalgam of 100+ personal reviews by people, many of whom may never have seen the lens, let alone handled it, let alone tried it, let alone used it, let alone tested it and evaluated its performance, on PhotographyBEWARE.com. Like I said, life is not that simple. How is it that two lenses that have near-identical "evidence" according to any qualitative indicator you choose (such as lines/millimetre or MTF) can so often produce hugely different qualitative results when tested side-by-side? It's because there is a lot more to lens performance than objective, qualitative data. Last year I decided to invest in new 35mm equipment for my photography business and meticulously researched every magazine review, optical test report, mailing list, web review site and Usenet newsgroup I could find. I even worked for two pro photographers without pay simply to learn from them - about technique as well as equipment. On the basis of what I learned, I made several purchases, only to find that not all the lenses lived up to my expectations. Yet they had good to excellent reviews and great ratings on PhotographyBEWARE.com and Photodo. So what went wrong? I assumed it was sample variation, and returned several items then bought again from a different dealer, to get a different batch, or bought used for the same reason. Except in one case, a lens which was damaged in transit, it wasn't sample variation. I then decided to do my own testing. Friends also got involved, and we tested a large number of lenses, sometimes several examples of each. We were particularly interested in wide angle zooms, and tried as many as four examples of one lens, the Cosina/Vivitar 19-35mm. Whilst we found we could easily identify which lenses appeared sharp, it was also clear that there were qualities in the images rendered by the lenses that just could not be quantified. And this is where testing for resolution and contrast falls down. That's "evidence" for you. As I said at the beginning, if only life were so simple. In the end, the best buying advice I have ever had is from other people who have used the lenses in a range of conditions, and who know the strengths and weaknesses of their equipment. But as far as you are concerned, that is "anecdotal evidence" or "opinion" which you consider to be "pretty useless". Not much hope for you, is there? ;-) -- Tony Polson
Date: Tue, 24 Apr 2001 From: Tony Polson [email protected] Newsgroups: rec.photo.equipment.35mm Subject: Re: This is why I own a Leica "Jeannie" [email protected] wrote: > Yes, how we view lens performance is subjective. I don't mind that people > have their personal opinions on lenses. For the most part, there's nothing > really wrong with them. However, I do object when personal opinion is posed > as indisputable fact. Where, precisely, did this happen? > I object when someone attempts to convince others of > the superiority of a lens over another by presenting a single picture, > against which there is nothing to compare. Superior? Superior to what? It > is perhaps demonstrated that such-and-such lens can do something wonderful. > It is not demonstrated that another lens cannot. I don't apologize for > being skeptical in the absence of better evidence. To be frank, I don't think anyone is ever going to convince you. This is something you're going to have to learn to judge for yourself. First you need an open mind and a willingness to learn. For many years I judged lenses by their resolution, contrast, control of distortion and control of aberrations. All except the last are completely objective, and the last is partly objective. I was also a fan of MTF tests, which combine resolution and contrast to give a good idea of the ability of the lens to register information. MTF tests are also objective. As a trained engineer I like objectivity and thrive on comparative data. Imagine my joy at finding a site on the Web which presented objective, comparative MTF and distortion data for hundreds of 35mm lenses. I was in heaven, all the more so because the site was Swedish and so am I. Then I started looking at the results for lenses I knew and had used. I spotted some inconsistencies and investigated further. What became clear is that you cannot judge a lens by sharpness, contrast and distortion alone. There is a lot more to it than that. The most difficult part of comparing lenses is trying to evaluate and compare those aspects of performance that are not so objective, and that are so often difficult to define. The one we're discussing here is bokeh, the quality of rendition of out of focus elements of the image. Mentioning bokeh on here is like waving a red rag to a herd of bulls. It invites ridicule, and those who discuss it run a high risk of sounding merely pretentious. But bokeh, or whatever you want to call it, is important. I think it is something that every keen photographer should be aware of, even though learning about it is not easy. Some lens manufacturers have considered bokeh at the design stage. Others trust to luck. Nikon has joined the manufacturers who design with bokeh in mind, even offering two lenses (105mm, 135mm) with what is effectively "adjustable bokeh". What convinced me of the real importance of bokeh was using a variety of Nikon lenses, most of which were sharp. Trouble was, if you compared the results from two lenses of equal sharpness, one would be more "pleasing" than the other, but it was not necessarily the sharper one. Unless you see this for yourself it is probably difficult for you to understand. Learning the importance of sharpness, contrast, sharpest focus, depth of field and defocused elements of a picture is not something that can be covered in a newsgroup discussion, especially one where people want to bludgeon others with their point of view - I admit some guilt here! I think the best way for anyone to learn is to work with a good portrait or landscape photographer. I did this by offering my services for nothing, and it did not take many calls to find one who was keen for some free help. Please don't be *too* sceptical; it can be completely unproductive. I was sceptical about aspects of lens performance other than sharpness and contrast for many years; I have no doubt that my photography suffered as a result. Try doing a Web search on bokeh. You may be surprised at what you find. -- Tony Polson
From: "Keith Wiebe" [email protected] Newsgroups: rec.photo.equipment.medium-format Subject: Re: Mamiya TLR Focus Problem (Revised) Date: Mon, 23 Apr 2001 Here's how you would see if it is focus. Open the camera back. Tape a piece of hair across the film gate. Now open the lens and hold open with a release cable. Shine a light into the back of the camera and focus the hair on the wall. Now see if the wall is in focus (keep it parallel to the camera) This is easier with a split prism focusing screen. I have done this to all my TLR's that I've had over the yrs and none of them were out. The problem is that these require careful focusing to begin with. Get a split prism glass and you'll be able to set focus a lot easier and more precisely. Keith Wiebe Andy-J [email protected] wrote > After examining the negatives more closely, I note that the both lenses > seem to be off by approximately the same amount (a 180 and an 80). > > I used the "newspaper at an angle" method--with the 80mm, the camera was > about 3 feet away from the focus point. With the 180mm, it was about 8 > feet away. The target wasn't *precisely* the same size on the neagtive, > but there was not a huge difference. > > The point of focus was not totally unclear on either lens--but the point > of greatest clarity on both was about 2 inches further away from the > point of focus. > > I find it interesting that both lenses are off by almost the same amount > and wonder if there is a focusing screen problem. This is a C330, and > the screen appears to be seated correctly. > the screen appears to be seated correctly. > > A few inches is not much of a problem generally--but I expect that this > focus discrepancy gets larger and the subject is farther away. Is this > just a "live with it" problem, or what? > > Also, has anyone ever tried adding shims to the focusing screen > itself--rather than cramming them in under the viewing lens?
From rollei mailing list: Date: Mon, 01 Apr 2002 From: Richard Knoppow [email protected] Subject: Re: Re: [Rollei] Planar Sharpness you wrote: >I have an F w/f3.5 Planar, 5 element version @ 1965. It is usually quite >sharp centrally at all apertures, but has to be stopped down to f11 to >achieve edge to edge sharpness. The lens looks good as far as I can detect >and has been examined by both Harry Fleenor and Marflex and pronounced fit. >I figured maybe curvature of field or film flatness issues. Could it >possibly be separation? How does that manifest itself on film? > >Allen Zak > Separation should be visible on examination of the lens. Shine a flashlight through it and look for bubbles in the cemented elements. The Planar/Xenotar is supposed to give better corner performance than a Tessar at the same stop. This lens should be doing better. Whatever the aberration is its more likely to be caused by a mis-spaced element or something of the sort. You can tell somethign about what is going on by putting a piece of ground glass over the film gate and examining the image visually using a magnifier. That will show whether the bluring off axis is due to field curvature or something else. Both coma and spherical aberration are reduced by stopping down. If the effect is not apparent on the ground glass it may be due to film flatness. An auto colimmator or laser interferometer could tell about this. Unfortunately, I've left my interferometer in my other suit. ---- Richard Knoppow Los Angeles, CA, USA [email protected]
Date: Sun, 10 Feb 2002 From: Richard Knoppow [email protected] To: [email protected] Subject: Re: [Rollei] 5 element Xenar you wrote: >I tried to use only the rear elements of the Unofokal. It works really nice >when stopped down to f:18, BUT I have to extend the bellows to max to focus >at infinitive, so portraits is out of the question. > >At larger apertures I saw a "shadow image" around lamps. I guess this is the >coma. > >/Patric Sounds more like either a ghost image from internal reflections or spherical aberration. Spherical looks like a cloud around bright objects. There is a blurred image with a sharper core. Ghost images can be blurred or sharp and will move relative to the object causing them as the camera is moved. Coma exists only off the center of the image. Its a tear drop or smeared looking blur of highlights. It can point in eiter direction but, in most lenses, points away from the center. It results in an unpleasant radial smearing of the image. You may be seeing a combination of two or all three of these. Goerz advertised the Dogmar as a triple convertible at one time. I doubt it was used much that way. As a complete lens its very good. Dogmars, which are similar to the Unofokal, were popular for use on one-shot color cameras. They had good color correction and the somewhat limited coverage angle was not a problem with these cameras since the lens had to be long enough to clear the beam splitter. ---- Richard Knoppow Los Angeles, CA, USA [email protected]
From: [email protected] (brian) Newsgroups: rec.photo.equipment.35mm Subject: Re: Lens sample variations (Nikon 24-85mm)- How to test? Date: 19 Apr 2002 awol eltee*@nr.infi.net wrote > I just bought a new Nikon 24-85 2.8-4D and am now starting to read > stories of more than a few bad samples popping up in this series. > > What sort of shots make good tests to see if you have a lemon or not? > I'm aware of the weaknesses of this particular lens, but I just want to > make sure I didn't get one of the "dogs". > > Thanks! > Lee Lee: The main thing to watch for is tilted and/or decentered elements. One of the best ways to test for this is to look for variations in the amount of color fringing in the four corners of the image. Also, if there is color fringing in the center of the image you've definitely got problems. If there's no fringing in the center and the fringing near the edges has rotational symmetry then you've probably got a decent lens. When testing for color fringing make sure you stop down to at least f/8. Here's a link showing what the color fringing looks like with the 24-85 when shot on a D1x camera: http://www.caldwellphotographic.com/cc02485at24.html Brian
From: [email protected] (brian) Newsgroups: rec.photo.equipment.35mm Subject: Re: Lens sample variations (Nikon 24-85mm)- How to test? Date: 20 Apr 2002 Denny: The CCD has very little to do with the color fringing you see in my test image. If you will take the time to examine all of the focal length positions for the lens in question you will notice that the orientation of the green and magenta fringes reverses direction when you zoom from 24 to 85mm. You can see this same phenomenon in the 50-135 zoom lens that is also documented on my site. Bear in mind that the exit pupil in the 50-135mm lens is absolutely stationary, meaning that the rays strike the image at precisely the same angle regardless of zoom position. Bottom line: the color fringing that I demonstrate cannot possibly be "the product of a CCD chip". How you can conclude that I am "condemn(ing) top end Nikkor lenses" is beyond my comprehension. Would you care to elaborate? The enlargements that I show are highly magnified in order to clearly show the aberration - corresponding roughly to a 112x160" print size. Have you taken that into account in forming your opinion? Also, I do show data for pro-caliber lenses, such as the 17-35mm f/2.8. I can assure you that the distortion correction that I demonstrate is very accurate. Anyone who has ever used the 24-85mm f/2.8-4.0 can tell you that it suffers from lots of distortion at the wide end. All I'm doing is re-mapping the image to get rid of that distortion. The effects that you object to are due to rectilinear perspective distortion and nothing more. Surely you are aware that objects near the edges and corners of a wide angle shot appear "distorted" in even when the lens has no geometrical distortion? If you don't believe me, then get a 24-85, shoot some architectural scenes, crop out the center portion corresponding to the size of a D1x frame, and then apply the correction factors that I have published. Who knows, you might even learn something. Brian [email protected] (Denny) wrote > Brian, I will respectfully submit that there is far more distortion > from the CCD chip in the digital camera, and from your computer > screen, than from the lens... And the color fringing you show is the > product of a CCD chip, not the lens.. > > A side point: your sample lens is a consumer item variable aperture, > not the high end glass, F2.8 constant aperture AFD, so one can hardly > condemn the top end Nikkor lenses based on on your samples... > > Now, in your sample picture, your "correction" adds more distortion > than it
removes... A case in point: > The white car at the left edge, just below center... Watch the ratio > of the hood length to the body length change between the 'distorted' > and the "corrected" photos... Now, follow the line of dark cars behind > this car back to the corner (diagonally up and right) and then counter > clockwise around the corner to the white car there... Watch the ratio > of hood to body there between the 'distorted' and "corrected" > photos... No ratio change, and the unchanged ratio is closer to the > ratio shown in the 'distorted' view, than the "corrected" view... In > the "corrected" view the hood length becomes too long, i.e. the car > becomes far more sleek than in real life... > > Also, the converging sidewalks right of center... When you correct the > 'distortion' the width of one sidewalk changes from the other... This > is your software, not the lens... > > Sorry guy, your digital machinations do not wash in the eyes of this > old photographer... > > Denny
From: Jean-David Beyer [email protected] Newsgroups: rec.photo.equipment.large-format Subject: Re: Testing new lenses Date: Mon, 06 May 2002 Greg wrote: > > How do LF folk test a new lens. Given that there seems to be always a poor > lens in amongst the good ones and that one needs to some time determine a > lens quality pretty quickly. Does anyone favour the bench test? A complex > detailed scene outside? > > If you don't have a competing lens to compare to, how would you go about it? > Does any one favour trannies over negatives for this purpose? I guess it depends on how bad the lens might be. I know how sharp I want a print to be. I shoot stuff on TMax-100 and process normally. If the stuff is fuzzier than I expect, I wonder about the lens. The only lens I ever had trouble with was a used Meyer Gorlitz Aristostigmat 120mm. It was much blurrier than I would have supposed (it is a dialyte). I took the thing apart and noticed that the retaining rings holding the elements had worked loose, so that the elements were not spaced properly, nor were they likely to be collimated. I just tightened them and the lens has worked fine ever since. It is slightly soft because it is uncoated, but not blurry. I would favor a bench test if I had a bench and knew how to use it, or had an optical shop nearby that I could walk in and have them test the lens, preferably while I waited (and the price was right). But in the final analysis, if the prints are sharp enough, great, and if they are not, not great. A guy named Curtis LeBel, president of the Audio Engineering Society in the 1950s (IIRC) had an axiom about audio equipment that I believe applies here: If it tests good and sounds bad, it is bad. Same with lenses. -- Jean-David Beyer
From hasselblad mailing list: Date: Tue, 14 May 2002 From: [email protected] Subject: Re: Re: [HUG] Mamiya v Hassy you wrote: >On testing optics... > >If they are of about equal high quality / satisfaction / perceived sharpnes etc., >when subjected to your most demanding uses... as seen by you, then they are both >great. > >No further testing needed, unless the testing process itself is of interest, or >the results are wanted for friendly photo geek argumentation...as in my lens is >sharper than your lens, and here is the objective proof etc.... While those are, of course, the main reasons I test lenses, it also saves time in discovering if they are satisfactory. Nothing beats actually going out and taking pictures with a new lens under a variety of conditions, but much can be learned from setting up controlled conditions and systematically observing results. I have culled out bad glass this way, and when too lazy to go through the trouble, have sometimes had cause to regret not having done so. >As an aside, if I understand current theory on optical testing and quality, high >sharpness could be defined as light going EXACTLY where it is supposed to, and, >unsharp could be defined as less of the light going to it's proper location , and >being instead elsewhere. AND, those two statements read identically if one substitutes >the word "contrast" for the word "sharpness". I.E. sharpness and contrast are >both names for pretty much the same characteristic, where the light lands. If >a lens puts the all the light where it is supposed to go, contrast and sharpness >are both simultaniously maxed out. > >Pretty elementary so far. Right? The interesting thing, which is corollary >to the above, is that essentially, the contrastier lens IS the sharper lens and >vice versa. Your contrastier Mamiya is probably a "sharper" lens. But since >you respond to both as being excellent, the differences are probably of academic >or lens owner status (...better toys make better boys...) interest only. Well, in terms of lines per mm resolution (1951 USAF), the Mamiya lenses outperform my Zeiss glass. But in 30X loupe examinations of negs and slides, there is no difference in sharpness my eye can discern. OTOH, my subjective impressions, after vewing many photographs made with both systems, is that the Hasselblad results are nicer. I don't think I have emotional attachments that subconsciously direct my preference, but then, I wouldn't know that for sure, would I? >There is probably a ton of room to define technical concepts and measures of sharpness >and contrast, and to debate their relative merits. I'll just be happy when the >lens can make results I like. >Charlie IMHO, film choice influences final results far more than lens differences. My only point is that those differences are noticeable, and if postings to these news groups are any indication, some people find them very important. I'm not one of them. Allen >> I use Mamiya 6 and Hasselblad with a number of lenses each. Both outfits >> produce about equal sharpness, but Mamiya is more contrasty. I prefer the >> overall look of images from Hasselblad, but the differences are not such as >> to influence my selection of one over the other for particular projects. >> >> It's a "bokeh" thing, not major on my list of considerations for lens >> performance. Others may find Mamiya lenses render image characteristics too >> harsh for their sensibilities. >> >> Why not arrange a side-by-side photo session with one of your Mamyista >> friends and do a comparison? That should answer most of your questions >> better than the opinions expressed here. >> >> Allen Zak ...
From: "Sherman" [email protected] Newsgroups: rec.photo.equipment.large-format Subject: Re: Testing new lenses Date: Sun, 12 May 2002 "Gilbert Dumont" [email protected] wrote > "Greg" > [email protected] wrote: > > >How do LF folk test a new lens. Given that there seems to be always a poor > >lens in amongst the good ones and that one needs to some time determine a > >lens quality pretty quickly. Does anyone favour the bench test? A complex > >detailed scene outside? > > > >If you don't have a competing lens to compare to, how would you go about it? > >Does any one favour trannies over negatives for this purpose? > > I shoot a (new) brick wall. Shows all the imperfections like > field curvature, blurr, misalignement of lenselements etc. > > G. Dumont I also use the brick wall technique. I will also shoot it at an angle testing depth of field and point of focus. I used a brick wall to test the packet films (Quickload, Readyload and Polaroid) all in a Polaroid holder to test whether the point of focus moved with different types of film. Focus on the GG and then put a piece of masking tape on the wall at that point. Put in each film packet and make the shot without changing focus. Check the negs and see if the point of focus is still on the tape. If so all the packets work the same in the holder. Also a good way to check whether newly purchased used film holders are properly aligned. (I've only purchased one *new* film holder in my life.) It was nice of the builders to install these lens testing facilities all over the place. ;-) Sherman
From: Gilbert Dumont [email protected] Newsgroups: rec.photo.equipment.large-format Subject: Re: Testing new lenses Date: Sun, 12 May 2002 "Greg" [email protected] wrote: >How do LF folk test a new lens. Given that there seems to be always a poor >lens in amongst the good ones and that one needs to some time determine a >lens quality pretty quickly. Does anyone favour the bench test? A complex >detailed scene outside? > >If you don't have a competing lens to compare to, how would you go about it? >Does any one favour trannies over negatives for this purpose? I shoot a (new) brick wall. Shows all the imperfections like field curvature, blurr, misalignement of lenselements etc. G. Dumont
From: "William E. Graham" [email protected] Newsgroups: rec.photo.equipment.35mm Subject: Re: How To Test My Lenses Date: Fri, 19 Jul 2002 "Alan Chan" [email protected] wrote > IMO, the best test is to use your lenses as usual. If you are happy with the > result, then keep using them. If not, keep searching. You wouldn't buy the > lenses just for tests, would you? No, but it would sure be useful to have a way to tell weather a lens is going to be good or not while you are standing in the store holding it in your hands...Few storekeepers are going to let you shoot through it for a week or more just to find out if you like it or not. Some enterprising optical engineer should design a portable box that you can attach a lens to and find out all about it right there on the glass counter...... Maybe something that shoots colored lasers through the lens onto a screen/ground glass and tells you how sharp and contrasty it is at the different wavelengths......I have a Vivitar TLA-1 "telescopic lens adapter" that I can carry with me and attach to a lens (Nikon mount) and look through it, but this doesn't really tell me enough. - Only that the lens isn't damaged or moldy......
From: [email protected] (Neuman - Ruether) Newsgroups: rec.photo.equipment.35mm Subject: Re: Tests of Long Tele Lenses Date: Sun, 04 Aug 2002 [email protected] (john chapman) wrote: >Thanks for your comments. > >This was the first time I had scanned film strips (normally only scan >slides) and I was having problems with the film strip holder. As to >the scratches... >I test all my lenses. I had never intended to publish the results >anywhere, so once I had satisfied myself as to the results, I was not >particularly careful how the film was handled and stored. > >The Nikon 400/3.5 is impressive optically, and provides a great max >aperture for high shutter speed and short DOF. However, the Sigma >50-500 has a street price something like 1/4 that of the Nikon, has an >incredible zoom range, provides very good optical performance that >seems to be second only to the Nikon, and has HSM focusing. There >will be times when the lens speed of the 400/3.5 will be required. >But for most shooting, I think the flexibility and focusing speed of >the S50-500 is a better choice. > >I think the 500mm test with this S50-500 shows pretty good corner >resolution. I suspect the corner resolution of some of the tests is >slightly less than what the lenses are capable since focusing at >something near 5.6 will not be as accurate as focusing at 3.5 . I >think both I and the in-focus indicator in the camera do better with >the brighter, shorter DOF images provided by faster lenses such as the >Nikon 400/3.5 . > >Anyhow, the web site was hit something like 39 times in the first 12 >hours it was up. I am pleased with the interest, and hope it is >helpful for some people. I think I will do some additional tests on >the S50-500 using ISO100 and 400 slide film. ISO100 will show what >the lens is capable of, while the 400 will show results using the film >speed most likely to be used with the lens. Probably, I will include >images at other focal lengths as well. Problems I saw in the tests: lens performance is not necessarily the same at near and far focus distances (it is often not, actually...), so checking resolution at only one (close) distance may not be a good indicator of how the lens performs for most uses; it is difficult to get the test-surface plane exactly parallel with the film, giving erroneous results for at least part of the frame (and lenses often *do* have tipped planes of focus, a useful thing to check for); it is VERY difficult to focus accurately on a planar subject, and *any* error will degrade the indicated performance in the test; more true for wide angles than teles, but B&W tests will often show different results from color tests in the image corners; a good test indicates the performance level in the far corners, at the far edges, possibly at the near edges, and in the center (it is likely that all three [four] locations will show different results - but if one is lucky, the four corners will be the same, as will be the two far edges [and two near edges]). For www.ferrario.com/ruether/slemn.html, I use comparative subjective testing, using infinity-focus large-area non-planar subjects (except for the close-focus checks) to reduce some of the problems noted above (it helps to have available a good, wide-angle view of a populated hillside top use as a "target"...;-). David Ruether [email protected] http://www.ferrario.com/ruether
from nikon MF mailing list: Date: Sun, 04 Aug 2002 From: Randy Holst [email protected] Subject: Re: Lens Hoods with Filters? "Kwan, Michael (FXMHQ MYS)" wrote: > > ...I noticed > that the hood is actually sitting at least 3 or 4mm more forward than > without a filter. Would this cause vignetting at larger apertures? In my experience, the Nikon hoods designated for specific lenses are designed so that a Nikon filter can be used with the hood without any vignetting. > I use Hoya > filters and the rings are rather wide. I notice that Nikon filters have > narrower rings. I have used Hoya filters also and have not experienced any vignetting problems. Unless they are very old filters, they aren't that much wider than Nikon's filter rings. > One more thing. Because I can't find a HS-11 for my E 50mm, I have this > opportunity to get a HS-7 instead. I notice on the box where it says it is > meant for the Nocturnal 58mm f/2.8 and the AF80mm f/2.8. Would the HS-7 work > for any of the standard 50mm lenses including the 2 AF 50mm's? Try finding a Nikon HR4 for your Series E 50/f1.8. Here's an easy way to determine if any lens/filter/hood combination will vignette: Mount the lens/filter/hood you want to check on your camera, set the focusing ring at the closest focus position, set the aperture ring to the smallest aperture and depress the DOF preview lever to close down the aperture and hold it there. Aim the camera at a brightly lit white wall and look through the viewfinder. If you can't see any darkening in the corners, the combination will not vignette. Randy Holst Boise, Idaho
From nikon mf mailing list: Date: Sun, 04 Aug 2002 From: Rick Housh [email protected] Subject: Re: Lens Hoods with Filters? ... >Mount the lens/filter/hood you want to check on your camera, set the >focusing ring at the closest focus position, set the aperture ring to >the smallest aperture and depress the DOF preview lever to close down >the aperture and hold it there. Aim the camera at a brightly lit white >wall and look through the viewfinder. If you can't see any darkening in >the corners, the combination will not vignette. That's exactly how I used to test for vignetting, when someone here (I'm sorry to have forgotten who), pointed out that the focal length of the lens shortens slightly as it is focused closer to infinity, and that actually a lens may vignette more when focused at infinity, all other things being equal. Now, when I test for vignetting, I still stop the lens down to its minimum aperture, but I test at both its closest focusing point and at infinity, using a bright sky for the infinity test. I have found that with some hoods, some lenses do indeed vignette when focused at infinity before they do at their closest focusing point. It seems especially true of "close focus" lenses, where the angle of acceptance at infinity can be considerably greater than when focused at some very close point. I have also found it helpful to place a fingertip at the corner of the frame, touching the edge of the lens hood, and move it slowly inward, to detect when it does appear. This gives me a better idea of how much leeway I have with that particular lens/filter/hood combination. If the vignetting is caused by the front edge of the hood or the sides, you can usually switch to a hood designed for a wider-angle lens to improve the condition. The HN-3 is a good universal choice for a "normal" lens under such conditions. However, if the vignetting is caused by the filter impinging on the field of view at the back of the hood/front of the lens, there's little you can do about that. - Rick Housh -
from nikon mf mailing list: Date: Mon, 5 Aug 2002 From: "Hansen, Lars Holst" [email protected] Subject: RE: Lens Hoods with Filters? Hello, Please note that a camera not having 100% finder coverage could pass this test and still show vignetting on the frame. Best regards, Lars Holst.
From rollei mailing list: Date: Wed, 28 Aug 2002 From: Bob Shell [email protected] Subject: Re: Vs: Vs: Vs: Vs: Vs: [Rollei] Rolleimagic is magic Richard Knoppow at [email protected] wrote: > Light from a nearby source has a spherical wave front. Think of > successively larger spheres of light radiating outward from, say, a candle. > If one looks at the surface of a small part of the sphere its curvature > becomes less with distance. This curvature approaches a plane without limit > as the source approaches infinite distance. In principal, a light at > infinite distance would produce plane waves at the viewing end. > It is possible to make a source of plane waves using a lens. By placing a > point source at the exact infinity focus position of the lens (by > definition, one focal length from the rear principal point) the other side > of the lens has plane waves comming out of it. In effect, the source behind > the lens appears to be at infinity. Such a source is very useful in both > measuring and adjusting optical devices. The lens must be well corrected, > otherwise it will not generate a sufficiently good replica of a plane wave. > The exact infinity focus position of a lens can be found by > autocollimation. You need a mirror of good quality and a source of light in > a focusing target. A hole poked in a sheet of print mounting cardboard will > work. Place a small flashlight behind the pin hole. Mount a plane mirror > over the front of the lens to be focused. A first surface mirror is ideal > but a second surface mirror will work. Adjust the lens mirror combination > so that the light reflected back from the lens is nearly concident with the > pinhole (it can't be perferfectly coincedent or you couldn't see it). Focus > for a sharp image. The lens is now focused exactly at in finity. The pin > hole will appear from the other side to be at infinity. > This trick is useful in finding the focal lengths of lenses, in finding > the principle points one the true focal length is known, and finding exact > infinity focus of a lens, for instance for setting the infinity stops or > focus scale for a press camera. Beautiful, Richard, simply beautiful. But, methinks you waste your time arguing with someone who has already made up his mind to be wrong. Bob
From nikon mailing list: From: "dplace" [email protected] Subject: Re: [Nikon] vivitar lenses/how to test clarity & contrast Date: Wed, 4 Sep 2002 > How would one go about testing the clarity/contrast of a particular lens. I've > done some comparison shots between the Vivtar prime, and my nikon 28-200 > 3.5/5.6 zoom and cannot see any discernable difference. Dave: we tested several lenses this past summer ... here's what we did ... remember "your milage may vary" ... first ... go out and use the lens ... this is not tongue in cheek ... you need to see what the lens will do as you will use it ... at the same time find something to test the lens ... we were photographing in a formal garden so there was a handy brick wall ... this will show you curvature of field ... the center will be in focus while the edges will be out of focus or show some other fault ... if you will be using the lens on a tripod as well as hand held shoot tests both ways ... trees against the sky showed us a fault on one zoom we were testing ... there was color fringing ... bad fringing ... in this case we chose a fixed focal length rather than the zoom ... check the lens at high magnifications as well as the size you normally work ... dplace DLPimages
From: [email protected] (Ted Harris) Newsgroups: rec.photo.equipment.large-format Date: 11 Sep 2002 Subject: Re: Rodenstock APO SIRONAR S 150mm F5.6 To further add to what Steve said. Quoting from the book "Image Clarity: High Resolution Photography" ..... "Sharpness is an aspect of image quality quite different from resolution. Whereas resolution is determined by how small image featheres are, sharpness is determined by how distinct their outlines are. ..... The percerption of sharpness is influenced mainly by edge contrast sometimes called edge definition ..... For more detailed discussions look at the highly technical discussions and mathematics of accutance. Cheers, Ted Ted Harris Resource Strategy Henniker, New Hampshire
From: "Al Denelsbeck" [email protected] Newsgroups: rec.photo.technique.misc Subject: Re: What exactly is saturation? Date: Tue, 01 Oct 2002 Ley Ying Low [email protected] wrote... > Trying to get my head around these terms. > What exactly is saturation and how does it differ from contrast? > How do you control it in photography? Saturation is how bright or intense a color appears. Highly saturated films may produce colors that look like posters, brighter and more intense than what the scene actually looked like before you photographed it. On TV, commercials for food usually have increased saturation. It is close to contrast, but not quite the same thing. Contrast is the difference in light levels in the photo. A B&W photo can have high contrast, but it has no saturation at all. For instance, http://wading-in.net/page70-Butterfly.html is an example of high saturation, but low contrast. There are very few truly light areas of the photo, but the green and orange are intense. On the other hand, http://wading-in.net/page10-ChurchHeron.html is an example of high contrast, low saturation. Not much color at all, mostly blue, but a larger range of lighter to darker areas. Fuji Velvia and Kodak E100VS (the VS stands for Very Saturated) are good examples of high saturation slide films. Lower saturation films are often intended for portraiture, like Kodak Portra (print film). This keeps blemishes on people's faces from being too noticeable. Slide films tend to look more saturated, but some of this is from shining a light through them to view. Fuji Superia, to me, seemed a good example of a higher saturation print film. Controlling it? First and foremost is using a film that has the saturation you desire. To reduce saturation, you can also under-expose slightly, or adjust exposure more towards the highlights of a scene (about the same thing). Shoot in subdued or more even light. If there's one color that you want reduced more than others, you can use a filter of the opposite color (i.e. to reduce red, use a cyan filter). But the film will do more than any camera effects. Hope this helps, - Al.
From: [email protected] (D Barry) Newsgroups: rec.photo.misc Subject: Re: What exactly is saturation? Date: 1 Oct 2002 Saturation is the strength or purity of a colour, controlled by the amount of or lack of neutral (grey/white/black )component. A vibrant 'fire engine' red is very saturated, but a dull, flat, greyish-red is de-saturated Contrast, on the other hand, is the difference in brightness/darkness between 2 shades of grey or colour. Both saturation and contrast can be controlled by lighting, choice of film, use of filters on camera lens. Strong directional lighting from bright direct sunlight will provide the most contrast, but soft diffused lighting lessens the contrast. Generally speaking, lower ASA/ISO films tend to exhibit more contrast than higher ASA/ISO films. In black&white photography, certain colour filters are used to enhance or subdue the contrast of the grey rendtion of different colours. And a polarising filter can often enhance the saturation of colour on colour film by selectively blocking reflected and impure colour tones. Saturation of a photo on traditional colour slide film can sometimes be enhanced by very slight, exact underexposure. And I read somewhere a long time ago, that saturation of traditional colour neg films can be enhanced by very slight, exact overexposure. Contrast of traditional film can also be increased by increased developing time in processing, or contrast decreased by decreased developing. In digital photography, some digital cameras and most digital image software (eg Photoshop, Paintshop Pro, etc . . .) have controls for increasing saturation and contrast. "Ley Ying Low" [email protected] wrote > Trying to get my head around these terms. > What exactly is saturation and how does it differ from contrast? > How do you control it in photography? > > Thanks > LYL
[Ed. note: a great point that many "bad" cameras may be just bad enlarger lenses ;-)] From leica topica mailing list: Date: Sun, 6 Oct 2002 From: Jeffery Smith [email protected] Subject: RE: On Picture Sharpness Disposables may be a bit too rudimentary, but I am currently dumbfounded by the incredibly high quality images being posted taken with "humble" cameras from the 60's and before. When I got my first Pentax, I was disappointed when I compared my results with those of a friend who owned a Nikon. I later dumped the Pentax and bought a Nikon and couldn't tell the difference (still mediocre). I later (6 years later) discovered that my enlarger lens (Durst, plastic I think) was the culprit. I now see the lowly Yashica RF producing excellent images for people, and the same with older Olympus and Canon RFs that were amateur cameras from the 1960's. I learned from the mistake of dumping my Pentax and its lenses that the weakest link in the chain is probably NOT the camera. Unless the camera is a disposable or a Holga. ;-) Jeffery Steve Unsworth wrote: > Well I have been toying with the idea of buying a few of disposable > cameras to do a picture of the week, but I'm not quite brave enough :-) > > Steve
[Ed. note: this post raises the point that it is critical to compare clean lenses, carefully checked for alignment and lack of abuse, and multiple samples, to reach valid results...] Date: Sun, 20 Oct 2002 From: "Scott Holt" [email protected] Newsgroups: rec.photo.equipment.medium-format Subject: Re: growing beyond my Yashica Mat Well, I think either some people read too much into my conclusion - I should have been more specific. My particular sample of an uncoated Tessar is sharper than my particular sample of a Yashinon. That having been said, I did what you and some others suggested and inspected the lens through a strong light. Its one ugly mess... I did the same thing upon taking delivery of the camera, but I must not have been using a strong enough light because I totally missed it then. I don't see how what I am seeing could have popped up in the last year. The inner surface of the rear element appears streaked - like the streaking you see when you use some cheap cleaner on your windows. Assuming this isn't not something worse, like separation or fungus, I'll clean it up and see what the results are - I expect they'll be significantly improved. That will take me a while since I don't have a spanner wrench (this is the perfect excuse to get one, though). - Scott "roland.rashleigh-berry" [email protected] wrote > Scott, just so we can help clear up the debate about Yashinon lens sharpness > and coverage compared to the Zeiss Tessar, could you please do an inspection > pof the Yashinon taking lens by opening the back, holding down the shutter > on "B" and looking through the back of the lens at an illuminated bulb about > 15 feet away. Is there any cloudiness or dirt in the lens that might account > for a lack of sharpness and lack of contrast? I know these cameras can > accumulate dirt on the inner surface of the rear doublet and this might > account for it. If it is clear then it would be useful to know so that we > know the comparison was a fair one.
From: "roland.rashleigh-berry" [email protected] Newsgroups: rec.photo.equipment.medium-format Subject: Re: growing beyond my Yashica Mat Date: Mon, 21 Oct 2002 "for7" [email protected] wrote... > >> >That having been said, I did what you and some others suggested and > >> >inspected the lens through a strong light. Its one ugly mess... I did the > >> >same thing upon taking delivery of the camera, but I must not have been > >> >using a strong enough light because I totally missed it then. > > > >Though coating streaks, if not serious, would hardly affect the results. > >Looking through the lens at an illuminated light bulb is a very harsh test > >of the optics. It will be very interesting to do this comparison again when > >the lens is clean. > > I agree but I believe "one ugly mess" meant more than just the streaks from a > poor attempt at cleaning. Then again if the streaking is a mixture that > includes smeared dirt then it would affect image quality. Kinda like wiping > your dirty windshield with a single piece of paper towel and doing nothing but > making it worse to see through. I agree with you that "one ugly mess" sounds more dirty than the common coating streaks you get from inexpert attempts at cleaning a lens. When I heard about this comparison between a coated Yashinon and an uncoated Tessar then it made me think there would be dirt in the Yashinon since the observed differences in quality were more than I expected. If Scott had said that the Tessar was sharper out to the edges but the Yashinon was more contrasty then I would have believed it without question. But with the Yashinon being less contrasty than an uncoated Tessar then it struck me that something was amiss. Also, Yashinon lenses saw professional studio use according to one of the posters here and I have heard of Yashinon shots being of competition quality so it made it seem doubtful. I'd definitely be interested in a new comparison between the two lenses once the Yashinon has been cleaned.
from manual minolta mailing list: Date: Tue, 22 Oct 2002 From: "Roland Reiss" [email protected] Subject: RE: 28mm primes test > this test showed very detailed infos, I was just to lazy to > translate all. Here some infos about the Minolta 28mm lenses: > 2,0/28mm: together with the Sigma significant better > sharpness than the Canon (F1,8) and Nikon (1,4), wide open as > well as stopped down two stops. Wide open visible vignetting > and distortion, no vignetting 2x stopped down. Best mechanics > in the testgroup. The test is, as usual in Color Foto, quite useless. It compares lenses at different apertures, i.e. the Nikon 1.4/28 stoped down to 2.8 and the Minolta 2.0/28 stopped down to 4. What I want is a comparison at wide open AND a 'common' aperture like 5.6 or 8. -- Roland Reiss
from manual minolta mailing list: Date: Wed, 23 Oct 2002 From: "Maisch, Manfred" [email protected] Subject: AW: 28mm primes test I agree, this is a weak point of most tests, also in other magazines. The only exception I know is Photodo, but they didn't release new tests foe ~2 years. One has to read all these tests with care. A single test of only 1 lens is of very limited value, but if a lens is tested several times in several tests over a longer period, it helps to estimate the quality of a lens, as most of us don't have the opportunity to compare a range of similar lenses directly. Manfred
From: "dr bob" [email protected] Newsgroups: rec.photo.equipment.medium-format Subject: Re: Checking focus accuracy on a TLR Date: Fri, 25 Oct 2002 Set up a yardstick at a slight angle to the normal lens axis with the closest end at the near end of the camera's hyperfocal distance. Place a "sharp" (pencil will do) object at the yardstick on the critical (camera indicated) focus distance. Stop the lens down as much as possible considering the available light. You might want to expose more than one frame varying apertures. This should tell you something and at least reassure you of the focusing mechanism. I remember the Yashica uses a cam? Be sure to use a tripod or other means of steady rest. Blur can be devastating in this experiment. Focus check at infinity is no problem, of course. Truly, dr bob. ...
From: [email protected] (ArtKramr) Newsgroups: rec.photo.equipment.medium-format Date: 25 Oct 2002 Subject: Re: Checking focus accuracy on a TLR ... Do this. Lay out the want ad section of the Sunday paper on a tabletop. Set your camera up so it is looking down at the paper at a 45 degree angle. Make a mark with a magic marker in the center of the paper. focus on the mark, Shoot wide open. Examine the negs. If the point of sharpest focus is on the mark you are right on and have no problems. If the camera is focusing fore or aft of the mark you have detected the errors direction and degree. It is a fast and accurate test. . Let us know how you make out. Arthur Kramer Visit my WW II B-26 website at: http://www.coastcomp.com/artkramer
From: [email protected] (ArtKramr) Newsgroups: rec.photo.equipment.medium-format Date: 25 Oct 2002 Subject: Re: Checking focus accuracy on a TLR ... >Set up a yardstick at a slight angle to the normal lens axis with the >closest end at the near end of the camera's hyperfocal distance. Place a >"sharp" (pencil will do) object at the yardstick on the critical (camera >indicated) focus distance. Stop the lens down as much as possible No. Stopping down gives greater depth of field and wipes out the focus accuracy test. Shoot wide open where any deviation from perfect focus will be immediately apparent. Arthur Kramer Visit my WW II B-26 website at: http://www.coastcomp.com/artkramer
From: Leonard Evens [email protected] Newsgroups: rec.photo.equipment.medium-format Subject: Re: Checking focus accuracy on a TLR Date: Fri, 25 Oct 2002 Ilja Friedel wrote: > KFritch [email protected] wrote: >>Art, I find this a little confusing. If I hold my TLR at a 45 degree >>ange to a newspaper, my viewing lens will be further away from the paper >>than my taking lens. > Not if you rotate it by another 90 degrees and hold it horizontal. > (Everything along a line across the newspaper should be in focus.) Or as others have suggested, you can tape a newspaper to the wall and point the camera at the wall making that 45 degree angle. Also, you should shoot wide open rather than stopped down to minimize depth of field. But there are a couple of things to worry about. First, it won't hurt to make sure the camera is level (and the wall is more or less vertical) by checking with a level. Second, and more important, you should refocus each time and run through a complete roll of film. Even if you use a loupe with the ground glass, you will find a certain amount of variation in just where you focus. This can easily move the focus an inch or so. If you make a sequence of shots, refocusing each time, you can determine the average focus position and thereby eliminate focusing error as a factor. Of course, if you systematically over focus or under focus, you will also see that. It will not be possible to distinguish that from differences of focus for the taking and shooting lens, but perhaps it doesn't matter. If you do discover a systematic difference between the two and it isn't very large, you can compensate when shooting. One thing I did was to remove the back from my Rolleiflex TLR and tape a small piece of ground glass there. Using a high power loupe, I was able to see where the exact focus was on the ground glass and compare with what the taking lens showed. But this test is also not definitive because the film will depart slightly from the ground glass position. Don't be surprised if, with the newspaper on the wall test, that the vertical locus of exact focus appears to be a curve instead instead of a perfectly straight line. Even very high quality lenses seldom have a perfectly flat field. My Rollei, which has a superb lens, at 8 to ten feet, showed a difference in best focus of a couple of inches or so from center to corners. Just going perpendicularly from the center to the edge would be less. -- Leonard Evens [email protected]
Date: Tue, 29 Oct 2002 To: Russiancamera-user [email protected] From: Bob Ludwig [email protected] Subject: [Russiancamera] Re: What makes the lens won't centered? You might wish to look at my and Paul Shinkawa's comments on the topic "Will Industar 61L/D Focus on FED2" that were posted on 10/28. Lens mounted on my FED 4b and FED 5c are properly centered when the lens threads are properly cut and the alignment of the lens flange is correct. Unfortunately, the Industar 61 and 61 L/D lens and some of the black Jupiter 8s and 9s were either abused or manufactured improperly. The new Industar 61 L/D that came with my new FED 5c has the same type of off-centering that you are experiencing. To verify that you do not have a flange alignment problem you will need to focus at a distant object with ground glass or semi-transparent tape placed between the film rails and examine the image on the tape or glass with a magnifying glass with the lens aperture at f2.8. In doing this, make certain that the lens distance indicator is at infinity (Some lenses "overrun" the infinity mark). Similarly, point the camera at an object one meter from the film plane with the lens distance mark set at one meter and verify that the image on the tape or ground glass is sharp. If these images are not sharp, either lens flange on the camera needs to be shimmed properly or the lens requires alignment. Bob Ludwig
From: [email protected] (brian) Newsgroups: rec.photo.equipment.medium-format Subject: Re: Is Zeiss batch testing lenses? Date: 1 Nov 2002 ...(query about batch lens testing..) Hi Bob: I have no idea what Zeiss does with their photographic lenses, but I do challenge the notion that 100% testing is rare and expensive. I once toured a factory in China in which small scanner lenses were 100% MTF tested using some fairly clever and economical equipment. I think that for this application is was critical that the lenses actually come very close to the design performance. It took only about 10 seconds to completely evaluate each lens. Mind you, these lenses undoubtedly cost less than $10! Another tidbit; on page 213 of "Eyes of Nikon" (a Nikon publication from 1985), there is the following quote: "As an additional benefit, MTF testing is incredibly fast (individual testing takes only 6 seconds!), so every single Nikkor or Nikon Series E lens coming off the production line can be tested." Brian www.caldwellphotographic.com
From: "David J. Littleboy" [email protected] Newsgroups: rec.photo.equipment.medium-format Subject: Re: why MF won't get better ;-) Re: What is depth of focus? Date: Mon, 11 Nov 2002 "Q.G. de Bakker" [email protected] wrote: > Where the "sweet spot" of a lens is depends on the particular design. Some > lenses perform best wide open, others need moderate stopping down. There is > no hard and vast rule. It's worse than that: resolution changes _differently_ with aperture at the center, edge, and corner for every different lens. (In some lenses it seems the corners are still getting better while the center is starting to get worse as you go from f/8 to f/16.) I presume you know this site, but for people who don't: http://www.hevanet.com/cperez/MF_testing.html David J. Littleboy Tokyo, Japan
From Minolta mailing list: Date: Sat, 8 Feb 2003 From: [email protected] Subject: Re: Vivitar 400mm/f5.6 [email protected] writes: Nice experiment but I believe you aren't accounting for another variable. The two lenses see two different amounts of area of the white wall, therefore two different amounts of light enter the lenses. If the white wall is evenly illuminated, that should be sufficient. This can be checked by taking close-up reading of different sections of the wall. Can't find a suitable wall? Another alternative is the northern clear blue sky. If you want to be even more exact, use a gray card. Set the lens focus at infinity, and move the lens close enough so that the gray card fills the viewfinder. The distance will be different with each focal lengh, but the exposure should be the same. Yet another alternative is to place a styofoam coffee cup over the front of the lens and point it at the sun. The reading will be the same for any lens at the same aperture -- except for light loss.
From: "Malcolm Stewart" [email protected] Newsgroups: rec.photo.equipment.35mm Subject: Re: Nikon 50mm f/1.8 AIS (old) vs. 50mm f/1.8 AIS (new) Date: Wed, 22 Jan 2003 Back in ~1974-5 I carried out some pseudo real-world flare tests at night by shooting the same scene including deep shadows and street lamps with a variety of exposures on Kodachrome. My SLR cameras were Minolta (MC lenses) and Canon with early FD breechlock SC lenses. (No access to SSC multicoated lenses. Minolta were claiming achromatic (double?) coating for their MC lenses.) I didn't use f22 but the results at around f5.6 to f8 were very revealing. Minolta's flare was much more diffuse than that from the Canon lenses where quite sharp edges were produced to the patches of different colour. (I took the precaution of removing the (probably single-coated) skylight filter for some of the shots.) Away from the flare the Canon images looked "cleaner" but I think overall I preferred the Minolta "look". I now use Canon EOS and have yet to repeat the tests with modern lenses - and our street lamps no longer have a wide spectrum tungsten lamp. -- M Stewart Milton Keynes, UK
From: [email protected] (brian) Newsgroups: rec.photo.equipment.35mm Subject: Re: Nikon 50mm f/1.8 AIS (old) vs. 50mm f/1.8 AIS (new) Date: 22 Jan 2003 ... Hi Chris: Shooting a bright sky should reveal the problem (if it exists in your lens) as long as the sky is exposed to give a middle or darkish grey (or blue). It would be a pity if Nikon is mistakenly using an inferior design for their latest version of the 50/1.8 when they had it done correctly decades ago. Fortunately there are plenty of the older lenses available on the used market. Brian www.caldwellphotographic.com
From: Larry Miracle [email protected] Newsgroups: rec.photo.technique.misc Subject: Re: Determining focal length... Date: Wed, 01 Jan 2003 Dam Francis, That's a much better answer than I came up with! Larry "Francis A. Miniter" [email protected] wrote: >I refer you to Stroebel et al, "Basic Photographic Materials and >Processes", Chapter 5 on Photographic Optics. > >The formula is [I/O] = [f/(u-f)] > > >where > >I = image size >O = object size >f = focal length >u = object distance > >It helps to know the vertical size of your film. So, if you are using >4x5 film in portrait format so that I = 5 inches, O = 60 inches, u = >600 inches, the solution for f would go as follows: > >5/60 = f/(600-f) = 1/12 which transforms to >12f = 600 - f >13f = 600 >f = 46 inch lens = 1170 mm lens, rather large. > >If, on the other hand, you are using 35 mm film in portrait format, so >that I = 1.5, then >1.5/60 = f/(600 - f) = 1/40 >40f = 600 - f >41f = 600 >f = 14.5 inch lens, or 370 mm lens, a bit more common. > > >Francis A. Miniter > > > >Antisprite wrote: > >>Is there an easy (or difficult) formula to find a specific, desired focal >>length. For instance, let's say I want to fill the frame with a 5 foot tall >>subject, from fifty feet away. What math, if any, will help me pick a lens? >> >> TIA >> Cheers
From: David Kilpatrick [email protected] Newsgroups: rec.photo.technique.misc Subject: Re: Determining focal length... Date: Wed, 1 Jan 2003 Antisprite wrote: > Is there an easy (or difficult) formula to find a specific, desired focal > length. For instance, let's say I want to fill the frame with a 5 foot tall > subject, from fifty feet away. What math, if any, will help me pick a lens? > To do it in your head, first know your frame size - 35mm vertical = say 30mm for a normally framed object allowing 3mm top and bottom. If you actually know the distance to your subject, that's a start since most people don't judge long distances very well. But let's say it was 100 metres. Your subject might be, say, 1.5 metres high (motorcylist on bike). You have to fit 1500mm into 30mm. Work out how many times 30mm goes into 1500 - 50. This is the scale reduction factor. You are reproducing your subject at 1:50 scale. Ignoring ALL of the aspects of macro work, large format relativity etc which call for more complex calculations, all distant objects (over 3 say) on 35mm film can have the lens focal length worked out by just dividing the subject distance according to the repro ratio. So, at 100 metres, subject 1:50 scale, divide 100 by 50. That's 2, or 2000mm. A vertically framed image of a motorcylist will just fit into the frame height at 100m distance with a 2000mm lens. This is not as complex as it seems. A normal standing person, on a vertical frame, needs to be reproduced at a 1:50 to 1:60 scale. On a horizontal frame, it's a 1:80 or 90 scale. On 6 x 4.5 rollfilm, it's more like a 1:50 scale for the horizontal format, group of standing people. So if you can only stand 3 metres away maximum, say in a room, you know you will need 3000/50 = a 60mm lens on 645. And if you are stuck with an 80mm, just do 80 x 50 = 4000 = 4 metres - you'll need a 4 metre space to be sure of comfortable framing. This does get simpler. You can treat 35mm vertical, and 645 horizontal, as more or less the same. 6 x 6 cropped to 10 x 8 print size is the same. You can use the 50 factor as a standing person benchmark, and it's easy to work out in your head. For 35mm horizontal, just increase distance by 50 per cent after working it out, or decrease focal length by a third. You can use 10 feet instead of 3 metres, if you find working in feet easier, and just remember that a standing person needs (more or less) a 50-58mm standard lens on 35mm vertical, a 35-40mm lens on 35mm horizontal. Most pro photographers very quickly learn than in a small domestic room you need a 35mm lens to do a full length, they never even think about working it out. But it does help to know. Then, if you are obliged to sit 40 feet away from a fixed point in a sports event, you can quickly say 4 x 35mm to get a figure in the height of a horizontal frame = about 140mm. So an 80-200mm zoom will be perfect for that situation. Or if you are 150 feet away, you'll know 15 x 35mm, or something around 500mm, will be needed. Think about this lot for a while, do some practical tests, forget about formulas and maths, and learn these simple relationships. Think of your subjects in terms of people height, it's easy to do. You will quickly learn to work out without paper what is roughly the best lens to fit, and after a while, you'll acquire the seasoned press photographer's ability to select a lens without thinking - or just rely on a 35-300mm! David http://www.freelancephotographer.co.uk/
From: [email protected] (Hemi4268) Newsgroups: rec.photo.equipment.medium-format Date: 03 Mar 2003 Subject: Re: RZ 110mm lens performance - comments (long) > Using a USAF resolution chart >from Edmound Scientific to read lines per mm (l/mm), TMax100 film,and >souped in D-76: > >Center/Middle/Edge/F-Stop >------------------------- >68 60 60 f/2.8 >60 68 68 f/4 >76 85 68 f/5.6 >76 76 68 f/8 >76 68 76 f/11 >68 68 68 f/16 >54 54 54 f/22 > In order to do this test right you need many more targets then just one. They should be placed at various distances to cover any possible mirror error. Just about all cameras have some mirror error. What I do is place targets at 16 ft, 18 ft, 20 ft, 23 ft and 26 ft. Sometimes even 29 ft. I then focus at 20 ft. This is called a thru focus test. Each distance from 20 ft shows about a 50 micron focus error. If you find that the 20 ft target is about 60 l/mm and the 23 ft target is 80, then you have about a 50 micron error. This is typical of most cameras. Just the fact that your higher resolutions are down around f-5.6 and f-8 tells me that you have this error. You best reso should be at f-4 You can figure the most error allowed is to square the f-stop. So f-1 would be 1 micron and f-2 at 4 microns and f-4 at 16 and so on. You see, at f-8 or 64 microns of allowable focus error your 50 micron mirror error is wiped out. Larry
From: "Richard Knoppow" [email protected] Newsgroups: rec.photo.equipment.large-format Subject: Re: Combining lens parts Date: Thu, 8 May 2003 Francois Hendrickx" [email protected] wrote > Richard, > > Thank you for your extensive reply. Many questions remain, > but the most important one right now is: how do I determine > what size lens I'm getting by removing, say, the front part of > a 150mm Symmar? Same as usual, by focusing at infinity > and measuring the distance from the film plane to the nodal point > of the lens (which will have shifted by the "amputation")? > > Cheers, > > Fran�ois My long original answer snipped. The exact focal length of any lens can be measured by focussing first on infinity and then for an image the exact same size as the object (1:1). The movement of the lens between these two positions is the focal length. You can double check this by measuring the distance between the object and image at 1:1, it is exactly four times the focal length. To focus exactly on infinity without a very distant object you can use a principle called autocollimation. This requires a small mirror, large enough to cover the front of the lens. It is ideally a first surface mirror but an ordinary shaving mirror will do. Just make sure you have a plane mirror, not a magnifying one. Place the mirror over the lens. It doesn't have to be touching, the distance from the lens really does not matter. Use a small light source, like a pencil flashlight to light up a spot on the ground glass near, but not exactly at, the center. A pencil mark on the ground side of the glass may help. Adjust the lens so that the reflected image is in focus. The lens is now focussed exactly at infinity. Note that the image does not always appear to come from the physical lens. The image comes from the rear, or second, principle point, which, by definition, is exactly one focal length from the image toward the lens when focussed at infinity. For single meniscus type lenses, which is about what the single cells of convertible lenses are, the principle point is often at the surface of one lens or in space outside of the lens. This can misleading if the lens is simply focussed at infinity and the distance from the ground glass to the center of the lens measured. For some types of lenses this can result in a large error. The error is obvious for telephoto or reversed telephoto types but exists for any lens. Since neither method of measuring given above depends on the location of the principle points they are accurate. Further, if you want to know the location of the principle points you have only to focus the lens at infinity and measure one focal length from the image to the lens. Knowing the location of the principle points is sometimes useful. For instance, if you want to calculate the combined focal length of two lenses the distance between them, which must be entered in the formula, is the distance between the second principle point of the front lens and the first principle point of the rear lens. Of course, it may be easier (and more accurate) to measure the FL of the complete lens by the method above. Exact 1:1 image to object size is easier to measure than some arbitrary magnification ratio. A good method is to use a small ruler as the object and place a similar ruler on the ground glass or to draw a scale on paper and place a duplicate on the ground glass. For purposes of using the lens and calculating the f/numbers great accuracy is not necessary. The _effective_ size of the stop, BTW, is often not its physical size. The stop is affected by magnification by the lenses. To find the effective size place an illuminated pin hole at the exact infinity focal plane (which you will have found by autocollimating) and place a translucent screen over the front of the lens. This can be thin paper. The size of the stop as projected on the paper is the _effective_ size and can be used to calculate the stops by deviding it into the measured focal length. --- Richard Knoppow Los Angeles, CA, USA [email protected]
From: [email protected] (Fernando) Newsgroups: rec.photo.equipment.medium-format Subject: Re: Lenses - yesterday, today and tomorrow Date: 20 Jun 2003 [email protected] (Bob Monaghan) wrote > On the other hand, MFers seem to do more with fewer lenses... ;) We can crop more! BTW, I've put up a comparison between some lenses I own. I used the same film (Provia 100F), and shot with 35mm, 6x4.5, 6x6. I then analyzed the results under a 40x microscope (not a top-notch stuff, actually, but I was able to see details that I was not able to see under my 12x loupe). I didn't publish the resulting numbers yet (too little spare time), and my test was not scientifical at all (I got slightly different charts for various lenses, for example), but nevertheless results are very interesting, at least for me! :) In particular, I was amazed by the resolving power and contrast of the venerable Zeiss Jena Flektogon 50/4 MC, that threatened the Pentax645 SMC 35/3.5 all the way along the resolution chart... I was able to (barely! :))) ) discern the chart pattern at 70 lp/mm at some apertures. I doubt the delivered contrast would be useful on real-world subjects at those resolutions, but it was amazing nevertheless, from an old retrofocus MF wideangle! :) I'll email you my report when it's done, so you may put it on your (precious!) web site if you want. Regarding lens evolution... well, my 2 cents are that we will see interesting improvements for prosumer-grade 35mm lenses. Not in speed or focal length, but in bulk, weight, stabilization and sharpness; thanks to the installed film cameras user base, and new digital SLR bodies with full-frame sensors. And in ultra-compact cheap lenses (for digicams) there's still much to improve: see the poor performances by the Zeiss Vario-Sonnar that equips the brand-new Sony DSC-V1. Bye! Fernando
From: [email protected] (Richard Knoppow) Newsgroups: rec.photo.equipment.large-format Subject: Re: Dallmeyer stigmatic f 6 9 inch lens Date: 8 Jun 2003 [email protected] (jimryder) wrote > I have had this lens for years, using it on a speed graphic. It seemed > sort of soft at the wider apertures but sharpened up stopped down. > Recently I discovered it seems to cover the ground glass on my 8x10. > It seems to be a convertible the back group is marked 14" but cannot > be used alone. The front element is not separately marked but appears > to be about a 12 inch focal length. The front group by itself is quite > soft wide open but again sharpens up stopped down and still appears to > cover 8x10. There is only one f stop scale marked f6, 8, 16...45. But > what are the correct stops for just the front group used alone? What > does stigmatic mean? and what is an approximate age for this lens? It > is uncoated. I have really enjoyed this lens and will probably explore > using the front group alone as a soft portrait lens on my 8x10. > Perhaps with the 4x5 back. So far its been a lot of fun. Oh dear, I missed a point in my other post. To find the stops you must measure the focal length. The procedure is to focus the lens first on an object distant enough to be "infinity" and then for 1:1 magnification. The difference in position of the lens is the focal length. You can also just measure the total distance from image to object at 1:1, this is four times focal length. If there is no convenient distant object you can focus for infinity by autocollimating the lens. You need a mirror large enough to cover the front of the lens. A shaving or makeup mirror will do but make sure the flat side is facing the lens. Put a pencil flashlight against the ground glass in the camera near but not exactly at the center. hang the mirror over the front of the lens. Focus the reflected image of the flashlight sharply. The lens is now at infinity focus. This does NOT tell you what the focal length is since you don't know the location of the second principle point. You need to make the other measurement also. Once you have the focal length you can determine the stops. When the lens is used in front of the iris you must measure the "effective" stop size, which will be a little different from the physical size of the hole in the iris, probably not much for this lens. Set the camera up at exact infinity focus as before. Place a sheet of tracing paper or other translucent material over the lens and place the pencil flaslight against the back as before. Measure the size of the circle of light projected on the paper. This is the size of the entrance pupil and the effective size of the stop. For convertible lenses used behind the stop the stop forms the entrance pupil so its physical size is also the effective size of the stop.
From: [email protected] (Hemi4268) Newsgroups: rec.photo.equipment.medium-format Date: 22 Jun 2003 Subject: Re: Lenses - yesterday, today and tomorrow >Film was a Fuji Provia 100F. You should not use film to test a lens. What you are testing is the FILM. Larry
From minolta mailing list: Date: Fri, 06 Jun 2003 From: "Paul Brecht" [email protected] Subject: Re: Bokeh ? I don't think that that's necessarily the best way to judge bokeh... Look at a typical shot (well, that could be anything I suppose) I'd say different types of shots. Try this: Studio Setting: set up a table of a few things & take many shots. Make sure that you have a strong backlight. At all relevant apertures, shoot 3 shots: 1. near focus, 2. correct focus & 3. distant focus. example: f/2.8 close/normal/distant f/3.5 close/normal/distant etc., etc... I'm not implying that you focus all the way close or at infinity, but close to... When choosing close/far focus, go all the way & back off a bit... Scenic: Do the same thing at all relevant apertures shooting 3 shots each. Do the same with portraits or whatever else you can test on... Report your results... Paul (dubbed a bokeholic by B. Wrainey) --- In [email protected], "annapoal" greenealan@a... wrote: > I didn't mean to get folks upset. My quick way to measure for bokeh > is focusing through tree leave at a light source. If the light > between the leaves goes smoothly out of focus without a center, a > dark ring next or a halo it is said to have, sorry, good bokeh. If > instead the light takes on the look of a dandylion that has gone to > seed with a center, dark ring around the center, and lastly a halo > ouside of that then it is said to have bad bokeh. Looks like smoe > sort of ball. I do feel that bad bokeh does detract from the image. > Sorry again, I do love my af 70-210 f/4 but it does not have good > bokeh. Just checked it to be sure. As for g and other minolta lens > check the minolta lens chart and you will find many have had changes > to try to improve bokeh which is primarily a function of the lens > diaphram. Love my minolta lens but not their bokeh and work to > minimize bad bokeh in shots. Have actually used a 40-50 year old > asahi 50mm f/2 with an 11 blade diaphram when bokeh was really > important. That old lens does not match the color or contrast of the > well coated Minolta lens but it has world class bokeh. Has anyone had > experience with the maxxum 7 feature to improve bokeh? How did it > work?
From: "Fredrik L�nn" [email protected] Newsgroups: sci.optics Subject: Measuring distortion Date: Fri, 2 May 2003 Does anyone have a good suggestion on how to measure the distortion of a (digital) camera lens. I would like to do it by capturing an image of a suitable test target and carrying out some kind of automatic/semiautomatic evaluation of the result. I found ISO 9039:1994 "Optics and optical instruments - Quality evaluation of optical systems - Determination of distortion". I don't know if it is applicable in this case, though. Best Regards, -- Fredrik L�nn Substitute "c" for "x" in e-mail address to reply.
From: [email protected] (Hemi4268) Newsgroups: rec.photo.equipment.medium-format Date: 17 Aug 2003 Subject: Re: zeiss ikonta for shooting? >At what distances? I found the novar is OK at normal P&S "group shot" >distances but falls apart as it aproaches infinity. For landscape uses it's >pretty bad. Most tests were done from 50 to 100 feet. About the distance needed to photograph a full size house with trees. One reason landscape images could look pretty bad is most true infinity focus points on folders are usually around the 50 to 60 ft mark and NOT the infinity mark. The infinity mark more often then not goes way past infinity resulting in out of focus images. Larry
From: [email protected] (Hemi4268) Newsgroups: rec.photo.equipment.medium-format Date: 16 Aug 2003 Subject: Re: zeiss ikonta for shooting? >Anyway, the Tessar lens is better than the pedestrian Novar lens. Now myself, doing resolution testing with real resolution targets, I have found the both lenses tend to produce about the same results. What really supprised me is that different shutter types resulted in higher or lower resolutions Seems if the shutter has a tight shutter release spring such as a Compur-Rapid, image motion is introduced even at high shutter speeds. Larry
[ed. note: will your next lens test be the straw that breaks your system? ;-)] From: [email protected] (Q.G. de Bakker) Newsgroups: rec.photo.equipment.medium-format Subject: Re: MF System with the most mechanical problems? Date: 27 Oct 2003 Bob Monaghan wrote: > On the other hand, I probably have learned to do a number of "tricks", > like checking flash cord synch and connectivity before loading film, or > flipping the lens stopdown lever to check action/release speeds before > mounting lenses, using the DOF button, tightening the film wind lever > backwards so it is tight and spins when the film is advanced (if the film > is advancing properly) etc. All these help keep Murphy's Law at bay, or > at least make it possible to feel confident about some things working and > error sources eliminated. [...] The eternal battle between hope (Pandora's most cruel "gift" to mankind) and fate... Being inhabitants of an indeterministic universe, we must (against our very nature, perhaps) learn to live with incertainty. We must dare to "live dangerously". Why? Murphy's Law will not be kept at bay. The extra stresses (small, but frequently repeated) put on the things you check by you checking them will very probably be the cause they fail rather sooner than later. If anything, you're helping Murphy's Law... ;-) It's like a mountaineer and his rope. How does he know whether it is or is not strong enough to catch his fall (and fall, Murphy says, he eventually will) and save his life? He can test it; tie a large enough weight to it and let it catch that. But then, how much strength will it lose because of this testing? And will it then still be strong enough? Will testing in fact not increase the likelihood that it will fail when it really matters? He can test it and use another rope of same type and manufacture. But no matter how you look at it, that particular rope, though similar, is untested... Testing, say, a lens stop down lever will tell you no more than if and how it functions during that test. It will indeed give you confidence (hope) that when it really matters, it will function as when tested. But will it...? Was your last test perhaps the last straw that broke the camels back...? ;-);-);-)
From: "Leicaddict" [email protected] Newsgroups: rec.photo.equipment.35mm Subject: Re: Leica Lenses vs. Zeiss Date: Fri, 14 Nov 2003 For the $4500 + you have invested, I wouldn't think otherwise. I'm looking at AF-S zooms from a more objective point of view, and also from a film point of view as opposed to a digital point of view which only uses the center portion of the lens. This is my procedure for testing lenses. Since I had 14 days to return the 28/1.4 and 85/1.4, I ran this test. Don't run this with your AF-S zooms, you'll lose to much money getting rid of them when you discover how disappointed you are. But keep this handy to test your next lens. 1. Back sections of the New York Times have pages completely covered with very small print. I tape these on a ceramic tile wall, evenly lite, at (or about) the closest focusing distance of the lens being tested, The newspaper print will alway fill the frame, so I can test corner, edge, and center resolution (with a loupe) at all aperatures (usually up to f11), and contrast. This is also a great test for centering and build quality. The 28/1.4 is soft in the extreme corners at f1.4, but since vignetting occurs in any lens wide open, this effectually obscures the softness. By f2.8, vignetting is gone and resolution now approaches the center. 2. 4 inch x 4 inch plain ceramic tile. Here, of course, it's nice if you have whole walls, like I do in my bathroom, of slightly off-white ceramic tiles. Here, one can test, not only distortion, but also vignetting. 3. Finally, I drive around and photograph Aluminum Storefront and Curtainwall, from a number is distances, with the camera as close to parrell and as level as possible. If there is any pincushion or barrel distortion at all, it will be visable. Distortion in the Nikkor AF-D 28mm/f1.4 is virtually non existent. All testing is done on a Gitzo tripod with film no faster than 200. Normally, I do not ever use a tripod. OK, occasionally a TableTop tripod is used as a chest brace. Hence, at least for me, the need for high quality, light, compact, lenses. -- THE REAL LEICADDICT ...
From: "Leicaddict" [email protected] Newsgroups: rec.photo.equipment.35mm Subject: Re: Leica Lenses vs. Zeiss Date: Fri, 14 Nov 2003 Don't know too much about lens, do you? There is no AF-S lens that can come close to either of these. Or to paraphrase, It's about the GLASS, Stupid! The AF-S lens you mention are zooms. All Zooms have very high levels of distortion, especially the AF-S 17-35mm and 28-70mm. I've used both of these lenses and haven't been impressed. They're big, heavy, expensive, and crappy, with quality of image no better than Nikons lower cost and lighter consumer versions. If you think the 17-35 is In fact, quality wise, a prudent selection of Nikkor primes in this range, will blow them away. If you think the 17-35mm is rectilinear, then you need to get your eyes checked. Expect for the fact thats it's a f2.8 (4 stops slower than what I use), it tests out no better than the lower cost, but comparable quality, 18-35mm. As I've stated, zooms suck. If you're happy find, perhaps my standards are too exacting. -- THE REAL LEICADDICT
From: "Bart van der Wolf" [email protected] Newsgroups: alt.comp.periphs.scanner,rec.photo.equipment.35mm,rec.photo.equipment.medium-format Subject: Re: how much resolution do we need (was Re: New Nikon Coolscan 9000ED) Date: Sat, 15 Nov 2003 "jjs" [email protected] wrote ... SNIP > Okay, seriously. That's one very trick algorithm. So a negative having 80 > lp/mm enlarged through a lens that does 80 lp/mm and with no other factors > (my perfect Focomat :)) theoretically produces 56.57 lp/mm. Then we add in > the enlargement factor, right? How do I plug that in? Divide by the magnification factor, but the result is still pretty crude. You would anyway need a system MTF to say more about sharpness rather than limiting resolution alone. Since human vision is the ultimate judge, you could attempt to shoot a test target and make an enlargement. Then with your particular workflow, measure the target and calculate the resolution. Such a target can be home made with little effort. I use a relatively simple star target, that gives both a visual impression, and the possibility to calculate the limiting resolution or an MTF (requires to take multiple measurements and calculations). It is easy to set up, use, and the interpretation is also very simple. I've uploaded a file (2 versions) for download. For HP inkjet printers (3.77MB): http://www.xs4all.nl/~bvdwolf/main/downloads/Jtf60cy-100mm_600ppi.gif For Epson inkjet printers (5.28MB): http://www.xs4all.nl/~bvdwolf/main/downloads/Jtf60cy-100mm_720ppi.gif Print this file unaltered (switch-off printer enhancements) at the indicated ppi setting (use glossy paper for output). It should result in a print of 100x100mm. Shoot an image of the target from a couple of meters distance (exact distance is not critical, 2-3 meters is fine). Using a tripod, mirror lock-up, and stopping down your lens to the optimal aperture will benefit the result. You may want to shoot several frames or targets at slightly different distances to eliminate (auto)focus variance and afterwards choose the best one. Evaluation: Measure the diameter of the unresolved center in millimeters on your enlargement. The star target image consists of 60 full modulation cycles from black to white, on a mid gray background. The circumference of any concentric circle will also equal 60 cycles, and measures Pi*diameter in length. Divide 60 by the length you find for your measurement and the result is the limiting resolution in cy/mm or lp/mm for your entire imaging chain. You can also approximate the MTF by performing multiple amplitude measurements along the circumference of various diameters, but that is easier if the image is digitized, so you can use software (e.g. "ImageJ" which can evaluate brightness profiles along a circular selection) to assist. Bart
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